Effect of Fulcrums on a Lever - info.ritenour.k12.mo.usinfo.ritenour.k12.mo.us/RSD/science_exemplars/k_5/pdfs/task265.pdf · their thinking and ensure that they are on the right track

Effect of Fulcrums on a Lever

After exploring levers, you now have some ideas about how theposition of the fulcrum affects the amount of effort needed to lifta load. Using a ruler (as a lever), a pencil (as a fulcrum) and 10pennies (as your load), investigate to find out which position ofthe fulcrum makes it easiest to lift the 10 pennies. You will needto make a prediction: Where on the lever/ruler does it make iteasier to lift (least amount of pennies used to lift the 10 pennieson the other side)?

Draw a labeled picture of your prediction: What does this modellook like? What is your hypothesis? Test the possible positionsand record your results in an organized way. Draw a labeledpicture of what worked, and state some conclusions about theposition of the fulcrum and about the effort applied.

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Effect of Fulcrums on a Lever

Suggested Grade Span

3–5

Task

After exploring levers, you now have some ideas about how the position of the fulcrum affectsthe amount of effort needed to lift a load. Using a ruler (as a lever), a pencil (as a fulcrum) and10 pennies (as your load), investigate to find out which position of the fulcrum makes it easiestto lift the 10 pennies. You will need to make a prediction: Where on the lever/ruler does it makeit easier to lift (least amount of pennies used to lift the 10 pennies on the other side)?

Draw a labeled picture of your prediction: What does this model look like? What is yourhypothesis? Test the possible positions and record your results in an organized way. Draw alabeled picture of what worked, and state some conclusions about the position of the fulcrumand about the effort applied.

Big Ideas and Unifying Concepts

Cause and effectModelsSystems

Physical Science Concepts

Motion and forcesTransfer and transformation of energy

Mathematics Concepts

Comparison of attributes or effectsData collection, organization and analysisGraphs, tables and representationsMeasurement

Time Required for the Task

Approximately two 45-minute sessions.



Context

This is one of several introductory investigation tasks in a unit on simple machines. Studentspreviously have investigated a number of concepts around this topic. In groups, studentsexplored a number of everyday machines, such as blenders, vacuums, telephones, etc., bytaking them apart to see how they work. They created a human machine to perform a specificwork task and looked at how machines are systems with inputs and outputs. They exploredlevers using rulers, pencils, and pennies and came to a number of ideas about levers and work.We investigated levers using a life-sized seesaw with students as the “load.” Using the aboveideas, as well as their prior knowledge and experience, students will control the variables ofposition of fulcrum and load (ten pennies) to see if their predictions about the position of thefulcrum are correct.

What the Task Accomplishes

This task is one of a number of guided investigations about each of the six simple machines. Itis used to teach and reinforce the idea that simple machines make work easier. In this task,students will learn that the closer the fulcrum is to the load, the easier the work is (in otherwords, less effort is needed). It also reinforces many science process skills, such as makingpredictions and hypotheses, collecting and recording data, and drawing conclusionsthat reflect concepts learned.

How the Student Will Investigate

After the initial explorations of levers, we discuss as a class some possible ideas about how tomake the work of the lever easier. This leads to exploring changes in the location/position of thefulcrum. We also use relevant vocabulary (load, effort, work, fulcrum) during these discussions.Students then write their testable question and make a prediction about where the position offulcrum will make the effort easiest. Students will need to decide how they will test this and howthey will record the data they collect. Students will use the materials to test their idea aboutwork and levers and then draw conclusions based on what they learned during theirinvestigation.

Interdisciplinary Links and Extensions

ScienceThere are a number of related activities with levers that students can do. Using the life-sizedseesaw (using a board as the lever), students can investigate lifting a variety of objects as wellas moving the fulcrum to explore its relationship to effort. Students can also look for levers thatare used in everyday life and explore how levers utilize a fulcrum’s position to make workeasier. Students can also investigate second- and third- class levers such as wheelbarrows andbrooms and the work that these do. Finally, students can discuss the saying from Archimedes,“If I had a place to stand and a big enough lever, I could move the world.”



Social StudiesStudents can research machines and tools, how they have changed over the years, and theirimpact on “doing work” in our lives. They can also research the invention or conception ofdifferent machines and simple machines and the people identified with these ideas.

TechnologyGive students a number of design challenges where they need to use simple machines to dowork. An example might be to move the teacher’s desk to a new location or to lift a heavy rockoff the ground. As a final activity in this unit, I have the students create a new machine thatutilizes at least three of the simple machines to make some type of work easier for them to do.They can be as creative as they want to be.

MathematicsStudents do measuring and comparing of weights, lengths, and heights frequently during thisactivity as well as in later activities in this unit. The mathematical concept of scale could also beintroduced in looking at sizes of machines and/or amounts of effort to lift significantly largerloads.

MovementMy students create a human machine – each person as a separate part that is connected to theothers and performs a different function in the machine to get the work done. We moved aheavy dictionary from one end of the room to the other.

Teaching Tips and Guiding Questions

Because this is an introductory investigation, it will be important to make sure that studentshave some understanding of the purpose of the fulcrum and have some ideas about how itsposition can affect work being done. Discussing the students’ ideas beforehand can help focustheir thinking and ensure that they are on the right track during the investigation. Some helpfulquestions to ask might be:

• Where is the fulcrum? the lever? the load?• What is the purpose of the fulcrum? What does it do?• What are the variables that will be controlled during this investigation? What will be

changed? How will you record the changes?• How does moving the fulcrum affect the effort (number of pennies) needed to lift the ten

pennies on the other side?• How will you organize your testing and your results so they tell you something?• Why does this position make the work easier? Harder? What ideas do you have about why

this is happening?• What conclusions can you draw about effort and position of the fulcrum?



Concepts to be Assessed

(Unifying concepts/big ideas and science concepts to be assessed using the ExemplarsScience Rubric under the criterion: Science Concepts and Related Content)

Physical Science – Transfer and Transformation of Energy: Students understand that energyis a property of many substances, that it is associated with mechanical motion and that a simplemachine uses energy (effort) to do work.

Physical Science – Motion and Forces: Students explain that a lever is a system; its input isthe effort needed and the output is the work done (the lifting). Students explain that work isdefined as moving an object from one place to another and that by moving the fulcrum (a part ofthe system) you change the amount of effort needed to do the work. Students use the termslever, fulcrum, load and work appropriately and describe cause-effect relationships with somejustification, using data and prior knowledge.

Scientific Method: Students observe and explain reactions when variables are controlled.Students see that how a model works after changes are made to it may suggest how the realthing would work if the same thing is done to it.

Mathematics: Students use tables and graphs to show how values of one variable are related(increase, decrease, etc.) to values of another. They use numerical data and (precise)measurements in describing events, answering questions, providing evidence for scientificexplanations and challenging misconceptions.

Skills to be Developed

(Science process skills to be assessed using the Exemplars Science Rubric under the criteria:Scientific Procedures and Reasoning Strategies, and Scientific Communication Using Data)

Scientific Method: Observing, predicting and hypothesizing, drawing and labeling diagrams,collecting and recording data, challenging misconceptions, raising new questions and drawingconclusions to communicate learning.

Other Science Standards and Concepts Addressed

Scientific Method: Students explain and communicate phenomena. Students control variables.

Scientific Theory: Students look for evidence that explains why things happen and constructan explanation based on their observations and the concepts they have learned.



Physical Science – Motion and Forces; Transfer and Transformation of Energy: Studentscan explain that energy is a property of many substances, that it is associated with heat, light,electricity, mechanical motion, sound, nuclei and the nature of a chemical and that it istransferred in many ways.

Suggested Materials

I supply rulers (either plastic or wood), pennies (enough so that students have 10 for the loadand at least 20 others for testing), and pencils to use as fulcrums. Other classroom objectswould also work well.

Possible Solutions

A correct solution will include the observation that the closer the fulcrum is to the load, theeasier the effort or work is. Students should also include the testable question, a predictionand/or hypothesis, a labeled drawing of their prediction and the position that was successful,test results that are organized (in a graph or table), and conclusions that accurately reflect datacollected and what was learned. Students should use appropriate vocabulary in theirexplanations.

Task-Specific Assessment Notes

NoviceThis student includes the testable question and a drawing of his/her prediction, although theprediction is not clearly stated. The test results are organized and labeled but are incomplete –not all positions were tested and recorded. There is a drawing of the position that was easiest,but it is not clearly labeled as such. The student includes a somewhat correct conclusion, but itis lacking detail and use of appropriate “scientific” vocabulary.

ApprenticeThis student includes a testable question and a drawing of his/her prediction. The prediction,however, is not written out, but it is fairly clear in the drawing and indicates what ideas thisstudent has about levers and fulcrums. The test results are complete but are not labeled asthey should be (effort = number of pennies and position = placement of the fulcrum). Data arenot organized so that a clear pattern can be seen. The student’s drawing of what worked thebest is clear, and the conclusion, while brief, demonstrates some conceptual understanding anduse of some appropriate vocabulary. Drawings should have shown pennies as the load andeffort (not, e.g., “16 tons” and “5 lbs”) and also should have included numbers on the ruler.

PractitionerThis student includes the testable question. S/he states a prediction and hypothesis. Thedrawing is well-labeled and detailed. The test results are complete, organized and well-labeled.There is a well-labeled drawing of what worked the best; it clearly shows what was learned. Thestudent’s conclusions demonstrate understanding of the concepts and indicate appropriate useof vocabulary. This student also begins to make some connections as to why the fulcrum works



better when closer to the load by stating, “The closer the fulcrum is to the load the more thelever does the work.”

ExpertThis student includes the testable question. S/he includes a prediction and hypothesis. Thedrawing of the prediction is very clear and well-labeled, indicating good overall understanding ofthe concepts. The results are clearly labeled, well-organized and complete. There is a drawingthat again is well-labeled, showing the position that worked the best (same as his/herprediction). The conclusions are complete and detailed. They indicate good understanding ofthe concepts and use of appropriate vocabulary. This student also makes connections, extendsthinking as to why this might be true, and clearly explains his/her ideas.



Novice



Apprentice



Practitioner



Practitioner



Expert



Expert



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Effect of Fulcrums on a Lever - info.ritenour.k12.mo.usinfo.ritenour.k12.mo.us/RSD/science_exemplars/k_5/pdfs/task265.pdf · their thinking and ensure that they are on the right track