The Methods of Science

INTEGRATED SCIENCE 9

The Methods of Science

Science

Science is a process that uses observation and investigation to gain knowledge about events in nature.

Major categories: Life science

Living things Earth Science

Earth Space

Physical Science Matter Energy

Investigating our World

Scientists learn new information about the natural world by performing investigations.

Can be done in a variety of ways: Observing and recording Experiments Using Models

The Scientific Method described the procedure commonly followed in scientific investigations

Scientific Method

Six common steps used in investigation1. State the Problem2. Gather Information3. Form a hypothesis4. Test the hypothesis5. Analyze Data6. Draw conclusions

Not all steps will be used every timeSome steps may be repeatedSome new steps may be addedThe scientific method is not a rigid process

Let’s break it down…

Stating the problem State the problem in a form of a question Make sure the question asks something that is

testable

Testable Questions

Why do people ask questions?

To a scientist, what do you think makes a good question?

What types of questions do you think aren’t suitable for scientific investigation?

Let’s Break it Down…

Researching and Gathering information Research is necessary to formulate a reasonable

hypothesis Sources of information:

Textbook Articles Expert Reference books Observations

Let’s break it down…(cont)

Forming a hypothesis Make an educated guess to answer the question you

are investigating Scientists frequently create a hypothesis with little or

no information As data is collected, a hypothesis is often refined

Testing the hypothesis Experiments or observation Experiments

Have only 1 independent variable All other variables are held constant

Let’s Try That…

An experiment is set up to determine what factor causes the greatest amount of liquid to evaporate.

Three containers of the same size each contain 100 mL of boiling water.

One container is steel, one is brass, and the third is aluminum.

The containers are allowed to sit for 20 minutes. What is the independent variable? How many controlled factors are there?

Let’s break it down…(cont)

Analyzing Data Using tables and charts Share data with others

Draw conclusions Does the data support the hypothesis? What do I need to do now? Rules of Thumb:

Don’t jump to conclusions The simplest solution is usually correct

Now we’ll put it all together…

In 1912, farmers in California found that it was cheaper to pick all the oranges at once regardless of whether they were ripe.

The oranges were placed in a small room heated with kerosene lamps and the oranges would ripen in a few days.

At some point, the farmer used an electric heater instead of kerosene lanterns. The oranges no longer ripened.

When switching back to kerosene, the oranges ripened.This was found to be true of other citrus.The farmers wondered what was so special about the

kerosene lanterns?

Here we go…

What is the question?What type of research would you do?Design an experiment.

What is the independent variable? What are the controlled factors?

Analyze the resultsDraw a conclusion

Observations

Test Your Observation SkillsM&M LabVariables Worksheet

Visualizing with Models

Sometimes when observing something that is too large, too small, or too time consuming, we need to use models

Models have been used frequently throughout history.

Models can be something you can touch or many models are created using computers.

Cowpea Mosaic Virus

Dams and Levees

Scientific Theories and Laws

A theory is an explanation of things or events based on knowledge gained by many observations and investigations Strongly supported hypotheses can become theories

Scientific Laws are statements of what happens in nature Laws do not offer explanation as to why

Theories Explain Laws!

Standards of Measurement

SI (International System of Units) is the share language for measurement in science Based on the metric system Uses multiples of 10 Each type of measurement has a base unit

Lengthmeter Masskilogram Timesecond Electric currentampere Temperaturekelvin Amount of a substancemole Intensity of lightcandela

SI PrefixesThe SI base units are not

always of convenient size for a particular measurement. The meter would be too big

for reporting the thickness of this page

The meter would be too small for the distance from Chicago to Detroit

SI includes a series of prefixes, each of which represents a power of 10.

These allow us to reduce or enlarge the SI base units to convenient sizes. 

Conversions Metric Conversion Ladder

A box weighs 1.25 kg. How many grams is that?

Kilogram (kg) is larger than gram (g) You need to multiply

(shift decimal to the right)

3 steps (3 zeros) 1.25 x 1000 = 1,250

grams

Conversions

Let’s try a few…

Conversion Worksheet

Measuring Distance

Choose a unit of length that is appropriate for what you are measuring For example,

cm for length of pencil m for length of classroom

Helps avoid using large digit numbers

Measuring Volume

The amount of space an object occupies is volume.Measure length, width, and height and multiply

the three numberslength x width x height = volumeExample: 10 cm x 10 cm x 10 cm = 1000 cm3

Remember: You have to multiply the numbers AND the units

Liquid volume is often measured in liters1 mL = 1 cm3

1000 cm3 is 1000 mL

Measuring Matter

Matter is anything that has mass and takes up space.

To measure mass, we use mass and volume.Mass and volume can be expressed as a ratio

called density

Density is a combination of two SI units. Combining two or more SI units results in a derived

unit. Can you think of other examples?

Accuracy and Precision

Accuracy Accuracy is how close a measured value is to

the actual (true) value. Correctness

Precision Precision is how close the measured values are to

each other. Repeatability

Communicating with Graphs

Scientists often use graphs and charts to display their result in order to better identify patterns

Graphs are useful for displaying numerical information.

Different graphs are useful for different types of information Line Graph Bar Graph Circle Graph

Line Graphs

Line graphs are useful whenever a dependent variable is changing due to a change in a independent variable

Dependent variables are y-axisIndependent variable are the x-axis

Bar Graphs

Bar graphs are useful for comparing information collected by counting.

Circle Graphs

Circle graph, or pie charts, are use to show how some fixed quantity is broken down

The pieces of the pie represent a percentage of the total