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Investigative Projects for Earth Science TodayRuss Colson
Following are eight example projects that you can do. Some of these project descriptions provide substantial details of experiments actually done with elementary or middle school kids, while others provide only a general outline from which an investigation can be developed. Regardless of which project you choose, I would hope that all of you use your own thinking and creativity to modify or improve upon your project. Certainly, you will at the very least need to identify the specific question that you are addressing and expand on the projects. Please talk to me regularly as you think through your project!!!! A big part of the purpose of this project is for you to interact with me, and think through your project with me. The purpose is NOT for you to go off and do something entirely on your own. Nor is the purpose simply to see if you can follow the directions in someone else’s pre-canned activity. The purpose IS for you to THINK about your experiment, identify problems with it, or changes that might make it more rigorous, to MODIFY AND IMPROVE it, to try knew approaches when your first approach doesn’t work, and to TALK TO ME about the experiment and how it is going and what your results mean. I am available in my office much of the day, in class during classtime, and by e-mail.
An investigation includes several steps: Asking a TESTABLE question, developing an experimental approach, testing out the experimental approach to see if it will work, constructing the experiment and doing it (with repetitions and controls), interpreting the results, and, finally, reporting the results. To get started in your thinking, and in understanding what an experimental investigation is, you should read over the notes and discussion of investigations on my web page.
1) Experimental investigation of stream velocity, and the relationship between stream velocity and sediment size.
Part I. An outline developed by a group of area teachersPart II. An investigation developed for 8 th graders by one of those teachers based on that outline Part III. A related activity on stream velocity and sediment size that I have done with 3 rd -7 th graders .
(an example project poster by Earth Science Today students)
2) Experimental investigation of the solubility of water in air as a function of temperature.(an example project poster by Earth Science Today students)
3) Experimental investigation of the distribution of salt between ice and liquid water
4) Observational investigation of lunar cratering and Experimental Cratering Processes.With a related companion investigation:
Experimental cratering investigationsExperimental cratering investigations in sand
5) Experimental investigation of the heat capacity of various materialsWith related companion investigations:
How do different colors of material absorb light energy differently?How does dirt in snow affect the snow’s rate of melting (outlined in “brief examples of
experimental investigations” on my web page)
6) Cookie Experiments (this is not really an earth science experiment, but might be an appropriate way to introduce elementary students to experimental investigation).
7) Experimental investigation of the relationship between air volume and temperature (outlined in “brief examples of experimental investigations” on my web page)
(an example project poster by Earth Science Today students)
8) Additional appropriate outlines for investigations might be found in the book “Two Suns and a Green Sky, Thomas Baker, 1994. Available at Concordia Library and in class.
1) Experimental investigation of stream velocity, and the relationship between stream velocity and sediment size.
Part I below is a teacher-developed outline of an experimental approach. Part II is an actual lesson developed by one of the teachers on the basis of this outline (for 8th graders). Part III is a related activity that I have done with 3rd to 7th graders.
Part I. Teacher Guided Inquiry: Stream Velocity Group: Pat Healey, Barry Olson, Tim Somes, Mary Colson, Karl Leonard Time frame: 2-3 weeks.1) Pose Question to students: What variables affect stream velocity?
Brainstorm a list, with teacher guidanceNarrow options downExample final list:
Slopedischargechannel roughnesschannel shape and size (width, depth)
2) Groups design their own experiments (kids need to know what materials they will have to work with)
Teacher must approve each design 3) Students conduct their experiments, record data, etc. 4) Groups will report results to classmates 5) Relate results to USGS stream data, for example, look at change in discharge over time. 6) Take a field trip to a local river Part II. The following extensive activity was developed by Teacher Mary Colson for 8th graders.
Part II. This comprehensive investigation was developed by Mary Colson for 8th graders, modified from an activity in “Crusty Problems”, ISCS, 1972. It involves students developing their own questions and experimental approach.Name _______________________________________________________________ Date ________ Period ______
Laboratory Research Activities: The Force of Moving WaterPart 1 - Learning to use the setup
IntroductionRivers and streams can be raging torrents or slow-moving trickles. Either way, they do
work on our landscape, making valleys, waterfalls, flood plains, point bars, deltas and other features. In order to study the work of rivers in the classroom, it will be necessary for you to use a stream trough or a stream table. The trough and table are simplified models of a real river or stream
The stream table or stream trough will allow you to control some of the important factors that influence a river's ability to erode or deposit. In nature all of these factors operate at the same time. In the lab you'll be able to control or vary the factors that you choose. For example, you'll be able to do such things as create a meandering river, speed up the water or slow it down, make it flow through different types of material, or increase or decrease the water volume in the river channel. By controlling these variables one at a time, in your model stream, you can begin to understand how real rivers behave. NOTEBOOK - define variable
The SetupThe standard setup is similar for all the stream table or stream trough experiments. In the
lab activities for our study of "The Force of Moving Water" we will begin by using a stream trough. Carefully examine the drawing below as well as the setup in the front of the classroom.
The Setup
The Materials Each group will have an assigned set of materials, the set number should be the same as your work table number. Each set should always have the following materials:
1 supply bucket (with supply hose) a plastic lift2 catch buckets (2/3 full of water) a beakera stream table a stream trough a pink sponge
You should always check before you begin the activity to see if you have all your materials. Let me know if you do not.
Do not carry any of the buckets by the handles. Carry the catch buckets to your workstation separate from carrying the stream table. Sometimes, you'll be able to leave the stream table on the window sill.
Some materials that you will have to get from me:1. a stopwatch (if someone in your group has a watch with a second hand that will work too)2. a screw clamp to control amount of water coming out of the supply hose
The Variables You will be able to easily control the following variables with your stream trough or stream
table: kind of sediment on the stream bed, the rate of water flow and the slope of the stream. You will need to practice controlling the rate of water flow (Part 2) and practice setting the slope of the stream (Part 3).
Name __________________________________________________ Date ________ Period ______Laboratory Research Activities: The Force of Moving Water
Part 2 - Learning to control the discharge
IntroductionMost of the experiments will call for you to adjust the rate of flow of water to a certain
number of milliliters per second. Doing this is easy. For example: you simply time how long it takes (in seconds for the supply hose to fill a 100 milliliter beaker. You can then calculate the rate of flow like this (the example assumes that it takes 5 seconds to fill the beaker):
100 milliliters (volume of water) = 20 ml/sec (rate of flow)5 seconds (time)
Practice the calculation.1. What would the rate of flow be if you filled up 100 ml in 10 seconds? Be sure to label your
answer with the correct units.
2. To achieve a discharge of 5 ml/sec, how long would you have to allow for the beaker to fill up to 100 ml?
Practice adjusting the rate of flow in the supply hose.4. READ THIS PARAGRAPH
Set up the stream trough with the lift and no boards. Put the lift as close to the closed end of the stream trough as possible. Set the supply bucket on the high chair. Next someone holds the supply hose high in the air, above the supply bucket. Another person fills the supply bucket by pouring water from one of the catch buckets. Put the screw clamp on the supply hose, tighten it so the hose flattens but is not squeezed shut. Put a finger over the open end of the hose and lower the hose into the stream trough. Place the empty catch bucket on a chair such that the water from the trough will end up in the bucket. Now remove your finger from the hose end and let the water run down the trough.
5. Change the tightness of the screw clamp and watch what happens to the amount of water coming out of the hose. Describe what happens when you tighten and loosen the screw clamp.
6. Stop the flow of water from the hose by putting the open end of the supply hose into the supply bucket or by folding the hose.
7. Now fold the hose and then loosen the screw clamp a little. Unfold the hose and let timing a small stream of water pours into your beaker. Find the 100 ml line on your beaker. I strongly recommend that you hold the beaker at the closed end of the stream trough. Remember to keep watch on how much water is in the catch bucket.
8. Empty the beaker. Time how long it takes to fill the beaker up to the 100 ml mark. Calculate the discharge.
discharge= 100 ml / time to fill to 100 ml
9. Now tighten the screw clamp a little. Repeat the instructions fro steps 7 and 8.
10. Calculate the discharge.
discharge= 100 ml / time to fill to 100 ml
11. Practice adjusting the discharge until you can get a flow of 10 ml/sec (anything between 9 and 11 sec is fine)
f. Practice adjusting the discharge until you can get a flow of 5 ml/sec. (any rate between 4 and 6 sec is fine)
3. Clean upa. We will usually return the room to complete order.b. Always dump the water from the supply bucket back into one of the two catch
buckets.c. Do not empty out the catch buckets in the sink unless Mrs. C. tells you to.d. When you need to transport the stream table, two people, one on either end, should
carry the stream table. Return the stream table to its correct place.e. Place all materials listed on page 2, back in the stream table.f. Wring the sponge out over the sink.g. Return screw clamps and stopwatches to me.h. Return your tables and chairs to correct position. Dry everything.i. Sit down :-)
Name ______________________________________________________ Date ________ Period ______
Laboratory Research Activities: The Force of Moving WaterPart 3 - Varying and calculating the slope.
IntroductionSometimes you will need to adjust the slope of the stream trough or stream table. You will need to raise the upper end of the trough or table a certain number of inches above the table. To change the slope, simply slip the plastic lift under the stream trough. Adjust the height of the closed end by either moving the lift towards the open end of the trough or by slipping a wood block or piece of cardboard under the lift. The wood and cardboard shims are located by the ___________________. Do not return them with your other materials to your stream table.
Practice1. Move the plastic lift as close to the closed end as possible. What is the distance between
the table top and the bottom of the stream trough? Measure in inches, to the nearest sixteenth of an inch. __________
2. Measure the "run" distance. Calculate the slope of the stream table in terms of inches per foot.
stream troughrise
runslope = rise (in inches)
run (in feet)
3. Move the plastic lift 13.5 inches toward the open end of the trough. If both ends of the trough rise up off the table, slide the lift back towards the closed end of the trough so that the open end rests back down on the table. Measure the height above the table of the bottom of the stream trough. Take your measurement at the closed end. ______
4. Calculate the slope of the stream table, in terms of inches per foot, for number 3.slope = rise (in inches)
run (in feet)
5. Move the plastic lift back to the closed end of the trough and slide 2 wood boards (or 4 cardboard shims) under the lift.
6. What is the distance between the table top and the bottom of the stream trough? Measure in inches, to the nearest sixteenth of an inch. __________
7. Calculate the slope.
Let the teacher see your work before continuing on.
Name _________________________________________________ Date ________ Period ______Laboratory Research Activities: The Force of Moving Water
Part 4 - Effect of discharge (volume per unit time) on water velocity
IntroductionNow you will experiment to determine the effect of changes in flow volume on water velocity (speed) in your stream trough. You will use 4 different flow volumes and measure the velocity of the water in the stream trough. To measure the velocity of the water you will time how long it takes a tiny piece of styrofoam to travel the length of your stream trough. You'll need to get the styrofoam from me.
Procedure1. Set up the stream trough as described in part 1. Keep the supply bucket half full at all
times.
2. Make sure you have a black "starting line" in your stream trough, located about 3 inches from the closed end of the stream trough.
3. Elevate the trough on the plastic lift. Line the plastic lift up with the closed end of the trough. What is the slope of the trough in inches per foot? ________ (you did this in Part 3)
4. Set your discharge to 20 ml/sec. Hold the hose in the trough such that the water begins to run into the trough right beginning at the closed end. Drop your bit of styrofoam into the water flow on the uphill side of the starting line and watch what happens.
5. Do step 4 again, only this time begin timing when the styrofoam crosses the line and stop timing when it leaves the stream trough. Record the value on the data table for Part 4.
6. Repeat step 5 two more times. If all three times are wildly different from one another, repeat several more times until you get some agreement among your measurements.
7. Repeat steps 4-6 again, but this time set your discharge to 15 ml/sec.
8. Repeat for discharges of 10 ml/sec and 5 ml/sec. NOTE for the lowest discharge, the bit of styrofoam will tend to get hung up. Try dropping the styrofoam in the very center of the flowing stream.
9. Graph your data on the grid provided. Put discharge on the x-axis and velocity on the y-axis. Make a line graph.
10. Use your line graph to predict the velocity of the water for 17 ml/sec. Write your prediction here________________.
11. Test your prediction. Time for styrofoam to flow downstream? _____ What is your measured flow velocity when the discharge is 17 ml/sec? _____. Compare the measured value with your prediction of #10.
Data table for Part 4The effect of discharge on water velocity
Discharge slope(in/foot)
Time for styrofoam to travel (sec) Average of times (sec)
Distance Styrofoam traveled
Water Velocity(in/sec)Trial 1 Trial 2 Trial 3
5 ml/sec
10 ml/sec
15 ml/sec
20 ml/sec
Name _________________________ Date ___________ Period ____
Laboratory Research Activities: The Force of Moving WaterPart 5 - Effect of slope on water velocity
IntroductionNow you will experiment to determine the effect of changes in slope on the velocity of the water in your stream trough. You will keep the flow volume the same. As with Part 4, you will use a small fragment of styrofoam to help measure how fast the water is flowing.
Procedure1. Set up the stream trough as described in Part 1. Keep the supply bucket half full at all times.
2. Elevate the trough on the plastic lift. Line the plastic lift up with the closed end of the trough. What is the slope in inches per foot? _______ (You did this in Part 3).
3. Set your discharge to 10 ml/sec.
4. Hold the hose in the trough such that the water runs down the full length of the trough. Lay the piece of styrofoam at the upper end of the trough and let if flow downhill and into the bucket.
5. Do step 4 again, only this time begin timing when the styrofoam crosses the line and stop timing when it leaves the stream trough. Record the value on the data table for Part 5.
6. Repeat step 5 two more times. Record your measurements.
7. Now change the slope by adding one wooden shim or 2 cardboard shims underneath the plastic lift to elevate it. Measure the distance between the table top and the underside of the stream trough. Record this value on your data table.
8. Repeat step 5 three times. Record your data.
9. Now change the slope again by adding one more wooden shim or 2 more cardboard shims under the plastic lift. Measure the distance between the table top and the underside of the stream trough. Record this value on your data table.
10. Repeat step 5 three times. Record your data.
11. Change your discharge to 20 ml/sec. Repeat steps 4-10 with the new discharge. Record your measurements on the data table.
12. Graph your data. Put slope on the x axis and speed on the y axis. Make two line graphs, one for each discharge. Label each line graph with the correct discharge.
Data table for Part 5Discharge = 10 ml/sec
Height above table
(inches)
trough length
(feet)
slope(inches/ft)
Time for Styrofoam to travel the length of the stream trough
Average time
Distance Styrofoam traveled (inches)
Velocity of water (in/sec)
Trial 1 Trial 2 Trial 3
Data table for Part 5Discharge = 20 ml/sec
Height above table
(inches)
trough length
(feet)
slope(inches/ft)
Time for Styrofoam to travel the length of the stream trough
Average time
Distance Styrofoam traveled (inches)
Velocity of water (in/sec)
Trial 1 Trial 2 Trial 3
Name ______________________________________________ Date ___________ Period ____
Laboratory Research Activities: The Force of Moving WaterPart 5 - Effect of slope on water velocity
Graph for part 5Change in flow velocity with respect to change in slope.
Name ____________________________________________ Date __________ Period ______
Laboratory Research Activities: The Force of Moving WaterPart 6 - Think about what you did and what you learned
Directions: Now that you have completed 5-7 days of experiments I want you to think about your experiments and think about the data you collected. What do the numbers and graphs mean?????? Please discuss the following questions with your colleagues in your research group. Each of you should then write, in complete sentences, your own understanding of the best answer for each question. DO NOT USE THE WORD "IT"! (The fill-in-the-blank questions don't require a complete sentence.)
Reflecting on the experimental design1. Describe the times when you or your group had trouble setting up the experiment or making any
of the measurements. Think in particular about the difficulty you had in setting the discharge, measuring/calculating the slope, getting the styrofoam to flow downstream with the water, and in timing the styrofoam. Describe those problems and how you solved them.
Analyzing the data - Part 42. Look at your graph for part 4. Make sure you have the x and y axes labeled correctly.
a. What variable is plotted on the x axis? _____________________
b. What variable is plotted on the y axis? ______________________
3. Plot your prediction for question #10 (or part 4) on your graph. Use a darkened square to mark the point.
4. Plot the velocity that you measured and calculated for # 11 (or part 4) on your graph. Use a darkened triangle to mark the point.
5. Does your measured velocity for # 11 fall on your line graph? ________. (In other words, does the velocity you measured for a discharge of 17 ml/sec match your prediction?)
6. When scientists do their own research, they will use their data to make a prediction. They TEST to see if their data really do make sense. If the prediction is wildly different from the measured value, the scientists would think that perhaps there was something wrong with their experimental design or with the way they conducted the experiment.
a. Discuss how well your predicted velocity matches your measured velocity for a discharge of 17 ml/sec. Why might the predicted velocity not match the measured velocity?
b. Now, as a further test of our experiments, check with other groups to see what their MEASURED velocity for #11 is. Record their data below. Draw a circle around your group’s velocity.
Group Number Measured velocity for a discharge of 17 ml/sec
1234567
c. Describe the variation among the data measured by the different groups. Discuss why this variation might exist.
7. The slope of the line on your graph illustrates the relationship between the two variables plotted. A line with a gentle and positive slope would indicate that a large change in discharge makes only a small change in water velocity. A line with a steep positive slope would indicate that a small change in discharge causes a large change in velocity. Many of you probably have a line
that actually curves. For example the slope is steeper for part of the line and less steep for part of the line.
Describe what the slope of your line says about the relationship between discharge and water velocity? In other words, describe the change in water velocity when you changed the discharge.
Analyzing the data - Part 58. Look at your graph for part 5. Make sure you have the x and y axes labeled correctly.
a. What variable is plotted on the x axis? _____________________
b. What variable is plotted on the y axis? ______________________
9. Look at the two lines on your graph for the effect of slope on water velocity. Describe, in general, the relationship between a change in slope and the subsequent change in water velocity. Your statements should be true for both discharges. Are there any unexpected patterns?
10. Look back at question 7 and reread the paragraph about how to interpret the meaning of the slope of a line.
a. Describe what the slope of your line (at a 10 ml/sec discharge) says about the relationship between slope and water velocity? In other words, describe the change in water velocity when you changed the slope.
b. Describe what the slope of your line (at a 20 ml/sec discharge) says about the relationship between slope and water velocity? In other words, describe the change in water velocity when you changed the slope.
c. Now, compare the slope the 10 ml/sec line with the slope of the 20 ml/sec line. Describe how the slopes of the two lines are alike and/or different.
d. What do your observations in letter c above tell you about how discharge (the volume of water in the stream) and slope interact to affect water velocity?
Making conclusions 11. In nature, what can you say about the influence that slope and discharge (the volume of water in
a stream) have on velocity of water in rivers and streams?
12. Turn in your textbooks to page 87 and read the two paragraphs about Slope and Volume of Flow. Do your conclusions support what the textbook authors say is true? Give an example.
Applying the conclusions to real rivers13. Describe some differences between real rivers/streams and your model stream that you used in
lab.
14. If you were to put sand along the bottom of your stream trough, what effect would the presence of that sediment have on velocity of the water flowing down your trough?
15. Look at the graph below. a. What variable is plotted on the x-axis? ___________________b. What variable is plotted on the y-axis? ___________________c. What variable in our experiments is the same as "discharge"? ____________________d. On what day or days would you expect the velocity of the water in the Red River to have been the greatest? Why?
Part III. River slope/velocity versus sediment transport experiment.(Materials needed for 14 students working in groups of 3: 5 flumes (downspouts), 45-50 blocks of uniform thickness of about ¾ inch, buckets to carry water, basins to catch water, 20 large particles of gravel (for example, about 1 ¼ inch), 20 smaller particles of gravel (for example, about 5/8 inch), 5 copies of blank graphs, 5 copies of example graph, pencils.)
Students will experimentally determine the slope required in a stream for gravel of different sizes to be washed downstream by the water. Two different sizes of gravel will be provided, which students will need to measure. Using 3 or 4 pieces of only one size of gravel at a time, placed in a flume (using a gutter downspout as a flume), students will gradually increase the slope of the flume, pouring water down it, until the gravel washes downstream. The gravel should be placed about half-way down the flume and the water poured in at the top (we aren’t interested in how a giant waterfall moves the gravel, but rather how a flowing stream moves it…..we will discuss with the students some of these experimental considerations). The observations for each slope of the experiment will be simply “gravel washed down” or “gravel didn’t wash down”. The results can be portrayed in a graph like the following that attached.
Discussion.
a) If have a steep, mountains stream, what kind of sediment at the bottom? (big particles) If have a slow, sluggish stream (like Red River) what kind of sediment at the bottom? (mud, silt)
b) Think of the beach experiment. Where is water moving more? (beach, not out in water) Where are the bigger particles? (where it is moving more, on the beach)
c) Suppose you find a dinosaur bone, and want to tell a story about where the dinosaur lived. How might you tell if he lived in a swamp or up in the big hills (hint: where will water flow fastest)? (look at size of sediment particles in the rock the dinosaur is found in- this is shale from an actual dinosaur site in South Dakota).
Num
ber o
f blo
cks
(mor
e bl
ocks
cau
ses a
stee
per s
lope
)
0
1
2
3
4
5
6
7
8
9
Smaller Gravel
Size = ____________________
Larger Gravel
Size = ____________________
Example Graph (but with arbitrary made-up measurements)
Num
ber o
f blo
cks
(mor
e bl
ocks
cau
ses a
stee
per s
lope
)
0
1
2
3
4
5
6
7
8
9
Smaller Gravel
Size = ____________________
Larger Gravel
Size = ____________________
Doesn’t wash away
Doesn’t wash away
Doesn’t wash away
Doesn’t wash away
Doesn’t wash away
Doesn’t wash away
Doesn’t wash away
Does wash away
Does wash away
Does wash away
Does wash awayThis slope washes away gravel.
This slope doesn’t wash away gravel.
Actual Graphs Constructed by kids after doing the experiments.
2) Experimental investigation of the solubility of water in air as a function of temperature.
This is one of the most common experimental investigations done in Earth Science Today in previous years. The investigation outlines in this section come from what student groups have actually developed and done. Pictures of a few of their reports are attached. Some of these have been very creative, coming up with approaches that I didn’t think of on my own.
How does rain come from thin air?
Understanding how rain or clouds form, a study within Earth Science, depends on understanding the chemistry of air, and how water can dissolve in the air, and how its ability to dissolve in the air is a function of temperature. Some background to put the chemistry in the context of the overall Earth Science puzzle : Clouds are formed from water that was dissolved in the air and condenses out in small droplets. We can watch water dissolve into the air when we boil water. The water becomes part of the air. When we set our cold Coke can out on a hot, muggy day, we can see the water undissolve, it condenses back out of the air. From these two observations, we can infer how the solubility of water in air (that is, how much water dissolves in the air) depends on temperature, which is the key to understanding how we get clouds. If you drew a graph showing the relationship between air temperature and it’s capacity to hold water, what would the graph look like? Dewpoint is the temperature at which water will start to condense from air as it is cooled. Dewpoint is therefore a measure of how much water is in the air. Relative Humidity is the amount of water in the air/amount of water the air can hold at that temperature x 100%. Relative humidity is therefore a measure of how much water is in the air compared to how much water the air could possibly hold at that temperature. Since cold air can hold less water than warm air, we can squeeze water out of the air simply by changing the temperature of the air (to make dew, or fog, or snow or clouds)! If we cool the air, it will hold less dissolved water, and some of that water will condense out as liquid or solid water. So how can we cool air? One way is simply to radiate energy away from the Earth at night (black body radiation). This cools the ground, which cools the air next to the ground. Under these conditions we may get dew, or frost, or fog as water condenses out of the air near the ground. But the big way to cool air for making clouds and rain is by adiabatic decompression (isn't that the coolest thing to say?). When air is compressed, its temperature rises. When air is decompressed, its temperature falls. You can observe this with a manual tire pump. The pump gets hot as you compress the air into your tire. Cans of compressed air can be purchased (for cleaning items you don't want to get wet). The nozzle of these get very cold as the compressed air decompresses on its way out. But maybe the easiest way to observe this effect is with a balloon. Blow up a balloon, then hold it against your cheek and let the air out quickly. You can feel the balloon cool as the air in it decompresses. Because pressure is lower higher up in the atmosphere, rising air will decompress and cool adiabatically. Air may rise because it is warm and buoyant (warm air is less dense and rises), or air may be forced up over mountains by winds, or air may be forced up by a cold or warm front. Regardless of how the air is made to rise, the rising results in decompression and cooling. The cooling can squeeze out the water dissolved in the air, and we get clouds and precipitation.
The evaporation and condensation of water is one of the main ways that Earth moves energy (remember that weather is the effort to even-out Earth's energy distribution). To evaporate water, you have to add energy to it (think about adding heat to boiling water, or how water evaporating from your skin takes energy from you and makes you cooler). That energy doesn't simply vanish from existence. When the water is re-condensed as rain or snow, we get that energy back. This is a major source of energy driving storms such as hurricanes, thunderstorms, and even winter storms. When water evaporates from the Gulf of Mexico, travels on winds up to Fargo-Moorhead and falls as snow in a big winter storm, the effect is to move a huge amount of heat from down closer to the equator to up here closer to the north pole! Some simple experiments students can do to measure the solubility of water in air as a function of Temperature: Experiment statement: In any experiment, you only want two variables to change, the variable that you are changing, and the response to that change. e.g. You can change Temperature, and measure the response of the air’s capacity to hold water, keeping pressure, air volume, and other variables constant. The following are experiments that students in my classes have come up with to measure the relationship between the air’s capacity to hold water and temperature of the air. Method 1: Observe the temperature at which a known amount of water can dissolve in a known volume of air at various temperatures: Get a large, clear, empty pop bottle (the bigger the better, but say 2 liters). You need the cap. Dry the bottle as much as possible by subjecting it to low-humidity conditions (warm, dry air). Put a small pin-hole in the bottle (this is so that pressure does not build inside the bottle when you close it up and change temperature----the air exchange through this pin-hole should be small compared to the overall experiment and not significantly compromise your results). Place a drop of water in the bottle (use an eyedropper so that the amount of water added is reproducible), along with a thermometer and cap it. Place the bottle in cold water, and gradually increase the T of the water until you see the drop of water completely evaporate in the bottle. Record the air temperature in the bottle. You can determine how much water is in one drop by dropping 100 drops in a graduated cylinder and dividing the amount by 100.Repeat this process for 2, 3, and 4 drops of water. Plot your results on a graph showing milliliters H2O soluble in 2 liters of air (or whatever your bottle volume is), versus temperature of the air. Method 2: Measure the amount of water that dissolves in air at a variety of different temperatures. Get several bottles (should be at least 2 liters) and a means to connect them to a smaller bottle or another 2-liter bottle (bottle connectors are available at scientific outlets, used for ‘tornado in a bottle’ demonstrations, or you can use some good tape if you seal it thoroughly). Poke a pin-hole in the two liter bottle (to allow pressure equalization when air in the bottles is heated or cooled). Add water to the other bottle (20-30 ml is plenty). Place a thermometer in the bottles to measure the air temperature. Seal the two bottles together, taking care that no water spills into the water-free 2-liter bottle. Bring the entire system to the desired temperature (placing in water bath, and controlling
the temperature of the water bath works well, so long as there is no leak -- the pin-hole can be at one end and left extending out of the water bath slightly). Give this system time to equilibrate (so that water vapor in both bottles equilibrates with the water present in the one). Then, detach and seal the bottle NOT containing the water (with bottle cap and tape over pin hole).Cool the entire bottle in an ice + saltwater bath (salt decreases the temperature of an ice-water bath which will be at 0C without salt). This will cause most of the water vapor present to condense. Cut open the 2-liter bottle and swab out the water inside with an absorbent cloth whose mass you have previously determined carefully. Redetermine the mass of the cloth quickly after swabbing out all the water (quickly, because water may be evaporating as you do it – watch how quickly the mass changes with time to get some idea of how much water may have evaporated before you got it weighed). Repeat this for other air temperatures, using additional 2-liter bottles. Plot your results on a graph showing milligrams H2O soluble in 2 liters of air (or whatever your bottle volume is), versus Temperature of the air. Note: For both of these experiments, larger variations in temperature is more likely to yield results that are not obscured by errors in the measurements. What are errors that arise in each method? Which is more precise? Which is more accurate? How do the results of the two methods compare?
3) Experimental investigation of the distribution of salt between ice and liquid water
This is an activity that I developed for 8th graders that illustrates the concept of what I do in my NASA-funded research. I did this activity in only a single class period, but it was very frenetic, and would be much better if expanded and spread over a longer time. This is a good example of the type of experiment that won’t work if the teacher hasn’t done it her/himself ahead of time and understand what is going on.
Students will be presented with an initial goal: determine what the saltiness of water volcanos on icy planets tells us about the amount of salt deeper in the planet. Students find another question that can be addressed experimentally that provides information to answer this question. (e.g. how much of the salt goes with water and how much stays with ice or solid salt?) Students will measure the distribution of salt between liquid water and ice. This measurement will be both qualitative (taste test) and quantitative (electrical conductivity). Experiments will be designed by the students. (should experiments be duplicated? how are variables controlled? How can experiments be done carefully?) Interpret the results of the experiments: Salt goes mostly into the liquid, by how much? Apply the results to the initial problem, what is the saltiness at depth in the planet? What model for what’s happening at depth do students choose? How can that model be further tested? Apply the results to other problems: Why isn’t rain over the sea salty? What happens when iceberg melt in the sea? What happens when sea water freezes?
Exploring Space From Earthusing experiments to answer questions about other planets
Russ Colson, Minnesota State University Moorhead
When the first rocks came back from the Moon in 1969, the question geologists asked was
"what has happened on the Moon in the past to make a rock like this?" We weren't able to do things on the Moon that we do on Earth to figure out how rocks form. For example, we weren't able to keep going back to the Moon, and we weren't able to excavate big pits to see what things look like deeper in the Moon's crust. So there was a big flurry of experiments on Earth to find out what kind of processes and events must have happened to get rock like the Moon rocks.
"Petrology" is the study of what rocks tell us about how they formed. The use of experiments to try to find how a rock formed is called "experimental petrology".
I am an experimental petrologist. NASA pays me to do experiments to figure out how rocks form on the Moon or other planets. Someday, when we establish colonies on the Moon or other planets, this understanding will help us know about our new world, find resources there to help us become economically independent of Earth, and anticipate the kinds of opportunities that other worlds offer us.
Here is a puzzle which you can solve that is similar in concept to the experimental petrology that I do.
Suppose that on some planet that is much colder than Earth, and the "rock" is made out of ice, you see a "volcano" that is erupting salty water. You figure out that the salty water comes from deeper in the planet where it got warm enough for a little pocket of ice to partly melt. The melted part erupted to the surface as watery "lava". The solid, icy part stayed behind inside the planet. Your question is this: Is the solid part left behind inside the planet JUST AS SALTY, or SALTIER, or NOT AS SALTY as the salty water "lava" that erupted to the surface? (Salty water eruptions are believed to have occurred on the Moon's of Jupiter, Europa and Ganymede) Hint: Think of an experiment you can do that will tell you whether more salt will go with the liquid part erupted to the surface, or with the solid part that remains behind.
Experimental design for measuring the distribution of salt between liquid and solid water
Russ ColsonMinnesota State University Moorhead
Materials: 4 paper cups (8 ounces work fine), 1 16 ounce cup or container, larger container about 6-7 inches in diameter and about 3-4 inches deep (such as a metal pan), crushed ice, salt, measuring cup, 1/4 teaspoon measurer, knife, spoon, and battery operated salinity tester (optional). Measure 3/4 teaspoon of salt into 1 cup of water in the 16 oz cup. Mix until the salt is completely dissolved. Fill one of the 8 oz cups about 1/2 full with this water. Mix crushed ice and 2 cups of salt in the metal pan to about 3/4 full. Add water just until the open spaces in the ice are filled. Place the 8 oz cup with salt water in the middle of the ice-salt mixture. Place a paper towel folded over several times over the cup (you may have to weight this down with something to keep the cup from bobbing up or falling over). Periodically stir the ice-salt mixture gently. The ice-salt mixture has a temperature below the freezing point of water. It will cause the water inside the cup to begin to freeze (This is how making home-made ice cream works too!). Allow about half of the water in the cup to freeze (the ice will freeze from the outside in, wait until the layer of ice extends about 1/2 to 1/3 of the distance to the middle of the cup). This will take about 20-30 minutes, perhaps less. Pour the remaining liquid from the cup into one of the other 2 8 oz cups and label it. Let the cup with ice sit for a few minutes until a teaspoon or so additional water has formed from melting of the ice. Pour this water off into another 8 oz cup. (The purpose of this is to get rid of some bubbles of liquid water that got caught in the ice - this water should be more like the liquid you poured off first than like the ice) Let the remainder of the ice melt (you can speed it up by heating in a microwave for 30 seconds or so). Pour this liquid into the empty 8 oz cup and label. This water is from the ice in your experiment. Now, in the experiment, the first liquid is like the salt water lava in the eruption on our planet. The second liquid, from the ice, is like the ice left behind deeper in the planet. Your question is: Is the ice inside the planet saltier, less salty, or the same saltiness. Each person in your group should taste each sample of water, from the first liquid and from the ice. Write down a "1" for the one you think is less salty and a "2" for the one you think is more salty. Compare your results to those of the rest of your group. Is one saltier than the other? Now, what is the answer to the puzzle: Is the solid part left behind inside the planet JUST AS SALTY, or SALTIER, or NOT AS SALTY as the salty water "lava" that erupted to the surface? Note: This experiment is qualitative, meaning you didn't measure the actual concentrations, only which one had more or less salt. You can make it quantitative by using a salinity tester to measure the actual concentration of salt in the water. However, you should be aware that little pockets of liquid water trapped in your ice contaminate your results and will make your results differ somewhat from the "true" distribution of salt between liquid and solid water. Note: A key difficulty with this experiment occurs if you do not make the salt-icewater bath cold enough. It is important to have lots of salt in a mostly-ice slurry. Otherwise, it will not get cold enough.
4) Observational investigation of lunar cratering.
The following activity was developed by Teacher Mary Colson for 8th graders.
Questions for the part looking at actual Lunar Craters: Consider the relationship between crater diameter and depth. Is there a trend relating crater diameter to its depth? Hypothesize why some craters are shallower than the normal trend. Are there any changes in trend? If so, what might cause that?
Observational investigation of Lunar Cratering.
NAME ___________________________ DATE _____________ PERIOD ________
PERFORMANCE PACKAGE FOREARTH SCIENCE AND INQUIRY:
The Earth-Moon System
Task 2: Make observations and formulate testable questions.
Summarize your observations: Use a topographic map of a portion of the moon to measure crater diameter and crater depth. Choose 9 craters of a wide variety of sizes.Map Name ________________________________
Crater Name elevation elevation depth diameter central peakapp. location rim bottom Y or N
Formulate questions: Is there a relationship between crater depth and crater diameter? Plot depth vs diameter on graph paper with the set up below. Label your points with Discuss with your research group. Describe what your group thought, is there a relationship between depth and diameter? (diam is how many times bigger that depth?
Crater Copernicus: Diameter = Depth =
Experimental investigation of cratering process. (This experimental activity used the same guidance for identifying testable questions as was used in Mary Colson’s unit for Question 5, Experimental investigation of the heat capacity of various materials. See that section for guidelines.
Formulate questions: Now, compare your list with the lists of those in your new group. Then, in your group, come up with questions about the observations on your lists. These questions should address the heating of earth’s surface. These questions can begin with “I wonder why . . .?” or I wonder if . . .? This activity will provide the foundation for you to develop a testable question.
a.
b.
c.
d.
e.
f.
g.
h.
Formulate a testable question: Craft a question that can be answered by you doing a controlled experiment. (You might try framing the question with “I wonder what will happen if I do . . . ?”) Remember during a controlled experiment you change one variable at a time and then measure the effect of the change you made. Describe how you might do such an experiment.
a. Our testable question is:
b. Describe, in 5 complete sentences how you might do such an experiment.
Another investigation with more direction on the type of questions to ask than that above for 8th graders is the following, which I have used with college students.
Experimental investigations of subsonic cratering processes in loose sand
A. In groups of 2-3, discuss what factors might effect the morphology (shape) and size of an impact crater. Make a list as complete as possible given the constraint that you only discuss it for 5-10 minutes. Give some indication of the relative importance you expect each factor to have.
B. The following questions are to be addressed experimentally, using the box of sand and various balls (impactors) provided. Mass and diameter of balls are given. The results are not completely analogous to hypersonic impacts, such as most primary impacts on planets, but give an idea of the way that the various important variables affect the crater size. I want you to try to design experiments yourselves (remembering to ask me lots of questions as you go along!).
Think about how to constrain your experiments such as to look at the effects of one variable at a time.
Think about how to conduct experiments so that results are reproducible (that is, the experiment can be repeated with more or less the same results). This requires that each experiment be done with the same initial conditions and in the same way. For each set of conditions, do the experiment 3 times or so to actually measure how reproducible your results are.
NOTE: Think about how to consistently measure the diameter of craters.
Here are some suggestions for things to think about.Question 1: Design an experiment to determine how crater size depends on velocity of the impactor.* Plot a graph which shows the experimentally determined empirical relationship between velocity
and crater size.* Describe your experiment (including how you controlled and measured variables and insured and
measured reproducibility) and observations :* Does the crater diameter vary linearly with increasing velocity (that is, if velocity increases by a
factor of 4, does the crater diameter increase by a factor of 4? (explain)* Based on your curve, do you expect the lines or curves to pass through the origin? * Consider the physical process that causes the relationship between velocity and size. Do you
expect on this basis that the lines or curves should pass through the origin? Why or why not?
Question 2: Design an experiment to determine how crater size depends on the mass of the impactor.* Describe your experiment (including how you controlled variables and insured and measured
reproducibility); show your results on a graph (don’t be sloppy).* Is the trend linear? Explain* Do you expect the line/curve to pass through the origin on either graph? why or why not?
Question 3: Are the variables Density, Mass, and Velocity all independent variables affecting crater size (meaning do they each cause an effect that cannot be predicted solely on the basis of the other variables values)? hint: You might, for example, construct an experiment to test the
hypothesis that crater size depends on Mass and Velocity, but that all the effects of density can be predicted based on mass of the impactor. * Explain your experimental design (including how you controlled variables) and your results.
Balls available for impact lab:
# available Diameter (cm) Mass (g) density (g/cc)Steel Balls
1 4.70 284.5 5.23 3.13 130.2 8.43 2.25 49.7 8.411 1.22 8.0 8.48 0.87 2.0 8.4bunches 0.61 1.1 8.4
GlassBalls1 2.83 30.9 2.712 2.44 21.3 2.715 1.60 5.5 2.714 1.25 2.5 2.7
WoodenBalls2 3.82 19.4 0.75 2.50 6.1 0.718 1.25 0.8 0.820 0.77 0.2 0.8
note: velocity = sqrt(2gh), g = acceleration due to gravity, h = height. g varies somewhat but is about 980.6 cm/sec2.
5) Experimental investigation of the heat capacity of various materials
The following activity was developed by Teacher Mary Colson for 8th graders. It was developed as a performance package to meet then-Minnesota requirements. I have only included Tasks 2, 3 and 4 from her comprehensive package of 6 tasks.
NAME ___________________________ DATE _____________ PERIOD ________
PERFORMANCE PACKAGE FOREARTH SCIENCE AND INQUIRY:
Weather - Heating Earth’s Surface
Task 2: Make observations and formulate testable questions.
Observations: In your group, discuss the evidence that the earth is heated or cooled unequally. Remember, the whole earth gets the same amount of incoming energy, and yet the surface of the Earth does not have the same temperatures around the world.
1. Describe to one another your experience (visiting, reading about, seeing movies about, etc.) that the earth does not have uniform temperatures. Take about 10 minutes for this.
2. List and describe all of the evidence and experiences that people in your group have had that demonstrates that the earth IS heated unequally. Follow the example listed in letter a.
a. seasons- warmer in the spring and summer, colder in the fall and winter.
b.
c.
d.
e.
f.
g.
h.
i.
Formulate questions: Now, compare your list with the lists of those in your new group. Then, in your group, come up with questions about the observations on your lists. These questions should address the heating of earth’s surface. These questions can begin with “I wonder why . . .?” or I wonder if . . .? This activity will provide the foundation for you to develop a testable question.
a.
b.
c.
d.
e.
f.
g.
h.
Formulate a testable question: Craft a question that can be answered by you doing a controlled experiment. (You might try framing the question with “I wonder what will happen if I do . . . ?”) Remember during a controlled experiment you change one variable at a time and then measure the effect of the change you made. Describe how you might do such an experiment.
a. Our testable question is:
b. Describe, in 5 complete sentences how you might do such an experiment.
NAME ___________________________ DATE _____________ PERIOD ________
PERFORMANCE PACKAGE FOREARTH SYSTEMS AND INQUIRY at the Middle Level:
Weather - Heating Earth’s Surface
Task 3: Design a controlled experimentDescribe what a controlled experiment is in the box below
A. State your testable question.
B. Predict what you think will happen. (This is a hypothesis)
C. Name the independent variable. You will change this on purpose.
D. Name the dependent variable. You will measure this.
E. Describe and draw your experimental set-up. Label your drawing. This will help you figure out what materials you need. Make a materials list. Your diagram should be detailed enough that anybody could look at it and do the same set up. Ideally, with the same set up a person could reproduce your experimental results!
Drawing of Experimental Set-up Materials List
F. Create a data table. Think about the measurements you are making and how will you record the data in an organized fashion. Make your data table below. Be sure to do it neatly.
NAME ___________________________ DATE _____________ PERIOD ________
PERFORMANCE PACKAGE FOREARTH SCIENCE AND INQUIRY AND TECHNICAL WRITING :
Weather: Heating Earth’s Surface
Task 4: Do your controlled experiment. Each group member should be gathering and recording data on their own data table that was developed in Task 3.
A. Do the experiment. Use this space to describe problems that come up and changes you made to your experimental design. (Having to make adjustments is normal)
B. Record your measurements on your data table that you made for Task 3.
C. Analyze your data.1. Start by graphing your data. Get graph paper from Mrs. Colson. Set up your
graph so that the independent variable is on the x-axis and the dependent variable is on the y-axis. Plot your points and make a line graph. Do not make a bar graph!!! Label the axes with variable name and units. Title your graph, include a key if necessary.
2. Look for patterns in your data. Describe those patterns here. Do not use the word “it”.
D. Identify factors that may have adversely effected your results. (What things did you do intentionally or unintentionally that could have messed up your data?)
E. Write two paragraphs discussing your interpretations of your data. Interpreting your data simply means figure out what the numbers tell you. Therefore, you might begin interpreting your data by considering the following questions:
1. What “answer” did your experiment give for your testable question? (Refer back to Task 3)2. How is the dependent variable related to the independent variable? (Hint: look at the slope of the line or lines
on your graph.)3. Is this relationship expected (think about the prediction you made in Task 3)? What was unexpected?4. Should your “line” really be a curve?5. If you tested multiple independent variables, what relationships did you see? (for example, different materials
and different amounts of cloud cover)6. Describe how your experimental results relate to your observations about heating and/or cooling of earth’s
surface.7. Discuss the impact of other factors that may have adversely effected your results.
In the space below jot down ideas from your group’s discussion of the above questions. Put these ideas down in your own words, do not copy each other’s word for word.
F. When you understand what your data mean, please write your two paragraphs summarizing your interpretations on a sheet of composition paper.
F. What conclusions can you make, based on your data?
G. If you were to do another experiment related to this one, what would you do? Why?
LAB ACTIVITYThis is an example of a precanned procedure (aka one way to do the lab) which Mary
Colson used with her students prior to developing the package above.WHY DO WE HAVE WARM AND COLD AIR MASSES
IN THE ATMOSPHERE ?
Step 1. Gather all the materials.Materials: 5 large Styrofoam cups
5 thermometers (use all of the same kind, glass, metal, plastic)Scissors1 150 watt bulb and lamp1 ring standruler
Step 2. Carefully cut the tops off the five cups about 3 cm from the bottom. Save both tops and bottoms of the cups. Not all classes will have to do this.
Step 3. Rig up your light and ring stand so that the light bulb is 15 cm above the table top. You may have to figure out how to keep your lamp from slipping. This is a variable we have to control. The lamp must be 15 cm above the table top for the duration of the experiment.
Step 4. Fill one cup bottom (nearly to the top) with water at room temperature. Get water from the 1 liter beakers by the back sink. Pour 100 ml of water into the 250 ml beaker and return to seat. Do the rest of your water pouring at your table. Fill the second one with dry sand, the third one with dry black dirt (be sure to break up any little clods). Fill the 4th one with dry sand and add room temperature water a little at a time until the sand is moist. Fill the 5th one with dry black dirt and add room temperature water a little at a time until the dirt is moist. Do not add more water.
Step 5. Arrange the cups in a circle underneath your lamp. See figure below.
Step 6. Place a thermometer in each container. Each thermometer bulb should be covered by no more than 0.5 cm of material (sand, water, dirt). Let your thermometers rest on the top half of the cups so a constant depth of burial if maintained.
Step 7. Don’t turn on the light until you record the initial temp. of each container.
Step 8. Turn on light and allow 1 minute to pass. Record temps of all 5 containers. Leave light on and continue heating containers for a total of 9 minutes. Read thermometer after 3 min, 5 min, 7 min, and then 9 min have passed.
Step 9. Turn light off and move it away. Read temp after 5 min of cooling and 10 min of cooling.
Step 10. Clean thermometers and return to front table. Dump out water from styrofoam cup into back sink. Return beaker to back sink and dump this remaining water into the 1000 ml beakers. Dump wet sand and wet dirt in correct containers on window sill. Rinse and dry those cups. Dump the dry sand and dry dirt back into their containers in the front of the room. Brush out the excess material. Return cups to front table. MAKE SURE YOUR TABLE IS CLEAN AND DRY.
Step 11. Graph your data. Ask Mrs. Colson if this is for homework or not.:-)
A companion investigation for this might be a study of how different colors of material absorb light differently (see below).
Measuring the affect of color on absorption of light energy:Note: This is a simple experiment in concept, but difficult to get results that make sense. I use this experiment as an exercise to give students an opportunity to FIGURE OUT HOW TO MAKE THE EXPERIMENT WORK. Once you figure it out, it is a very easy experiment to do and understand.
Objective: Measure the rate of heat absorption by different colors of paper (black and white, or you can add other colors).
Stuff: white paper, black paper, water, beakers of water with white and black paper, high-wattage lamp, thermometers
Considerations: the distance the light bulb is from each experiment and the duration of insolation is important! Where you put the paper affects the results (for example, the glass beaker acts as an insulator so if you put it on the outside, but measure the water temperature inside the beaker, your results may not make sense). The wattage of the light bulb is important (if heat is being lost to the room faster than heat is added from the lamp, you won’t see a temperature change. Also, the wavelength of light is important.....a heat lamp provides more long wavelength energy, which is absorbed differently by the paper, than does a typical incandescent bulb). To get heating rate, you must think about temperature as a function of time (what might you graph?)
6) Cookie ExperimentsThe following investigation outline was developed by teachers at a NASA sponsored workshop. It was developed for middle school students, but is maybe a bit too unrelated to earth science for that age, but could be readily adapted to be appropriate for elementary students, exposing them to the concept of experimental investigation.
Experiments in Cooking, by Lois Ewertz, Mike Finneseth, Russ Colson In groups of 4, students will1) Identify some recipe they want to study, e.g. cookies, pudding, bread. 2) Identify at least one measurable response (dependent) variable and four variables that can be controlled and changed. 3) Each student will be responsible for experiments changing one of the changed variables, and measuring the response of at least one response variable. They will hold other variables constant. 4) Students will get together with the rest of their group to think about how their variables might interact with each other. 5) Students will make a presentation to the class with their group, and make a written report of their component of the study. Their report should identify the changed (independent) variable(s), the response (dependent) variable(s), and variables held constant. It should include a graph showing the experimentally measured relationship between the changed and response variables in their study. Grading:
Presentation: Each student presents their component of the results to the class as part of their group report: 25%
Individual Grade, written report: 75%writing quality and correctness in explaining experimentidentification of variablesgraph
Examples:Cookies:
Variables that can be changed: Temperature, cooking duration, proportions flour/Crisco, use of something other than Crisco (lard, butter, other vegetable shortening), baking sheet composition (heavy metal, light metal, glass)
measurable response variables: cookie thickness, diameter, density, chewiness, flexibility vs brittleness, brownness. Bread: Could measure crustiness by how much weight is needed to push a nail into it, or could measure bread density (mass/volume) by cutting a cube of known size and measuring its mass. Pie: could measure runniness by how quickly a fixed amount of filling spreads out to a given diameter circle (diameter/time).
Notes and thoughts: students can come up with their own variables. This will help them think about the controlled and response variables. But if students are not able to come up with a measurable response variable, the teacher can guide them toward some other baking item.
