The Scientific Method

What is the scientific method?

• A systematic approach to problem solving.

• A method that is applied in all scientific investigations.

General Steps of the Scientific Method

• State the problem. (Purpose)• Gather information on the problem.

(Research)• Form a hypothesis.• Perform experiment(s) to test the

hypothesis.• Record and analyze data.• State a conclusion.• Repeat and/or redesign.

State the Problem

• This is the purpose of the investigation.

• State what problem you want to solve or what question you want to answer.

Gather Information (Research)

• Use various resources to inform yourself about the parts of your investigation. This involves research!!

• You must educate yourself about your investigation so that you can make a hypothesis to test.

Develop a Hypothesis

• A hypothesis is a possible explanation for a set of observations or answer to a scientific question, must be testable.

• The hypothesis is what you are testing in an investigation.

• Let’s choose an example and work through the first three steps of the scientific method together.

My car will not start!!!

• What’s the problem?

• How can we gather information about the problem?

• What are some possible hypotheses we could investigate?

Perform the experiment

• Design and perform an experiment that will test your hypothesis for accuracy.

• To do this you must be able to identify your variables.

Variables

• The “thing” that is being changed by you - by your manipulation.

• There can only be ONE manipulated variable.

• The “thing” that reacts (responds) to what you have changed (manipulated).

• This is the “thing” you are measuring.

Independent or manipulated variable

Dependent or respondingvariable

One more type of variable...

• These are the “things” that stay the same throughout the investigation or experiment.

• In the setup of your experiment, you can only have one manipulated variable, this means all other variables must be controlled (kept the same).

Controlled Variables

Back to the Car….

• Possible hypothesis: If gas is put into the car, the car will start.

• What’s the manipulated variable?

• What are some controlled variables?

• What is the responding variable?

Record and Analyze Data

• Data includes the measurements and/or observations you make about the responding variable.

• But first, you must determine what type of data (called observations) you will collect.

Types of Observations

• Observation that measures such things as size, weight, distance, volume, etc.

• This observation MUST use a number.

• Observation that describes using details such as size, color, shape.

• This observation uses NO numbers.

Quantitative Qualitative

Examples

• Jane is five feet tall.

• There are 65 cars on the train.

• I wear a size 8 shoe.

• The gas tank holds 18 gallons.

• Jane is taller than Jack.

• The walls are gray.

• Oranges are round.

• Jack is heavier than Jane.

Quantitative Qualitative

Quantitative or Qualitative?

• Which type of observation is most useful in a science investigation?

• QUANTITATIVE!! Why?

State the Conclusion

• Your conclusions should consist of your best explanations for given observations.

• Your conclusion should answer the questions: What happened? and Why did it happen?

Repeat and/or Redesign

• In order to confirm results, you should always repeat your experiments numerous times. If there are ways to improve your experiment, you should redesign it until it properly tests your hypothesis.

• Remember! A single experiment never “proves” a hypothesis to be true, it only supports or does not support a hypothesis.

Let’s apply what we’ve learned….

Apply what you’ve learned…..

• To test whether aspirin can keep flowers fresher for a longer period of time, take two large beakers (labeled A and B) with equal amounts of water. Place one red carnation in each beaker. In beaker A put one tablet of aspirin. In Beaker B do not put aspirin. Identify the following with regard to this particular experiment.

What is the manipulated variable?Amount of Water Aspirin

Carnations Time the flowers stay fresh

Apply what you’ve learned…..

• To test whether aspirin can keep flowers fresher for a longer period of time, take two large beakers (labeled A and B) with equal amounts of water. Place one red carnation in each beaker. In beaker A put one tablet of aspirin. In Beaker B, do not put aspirin. Identify the following with regard to this particular experiment.

What is the responding variable?Amount of Water Size of beakers

Size of carnations Time the flowers stay fresh

Apply what you’ve learned…..

• ”If the amount of sunlight available increases, the rate of photosynthesis in a plant will also increase".

This statement is an example of a(n) Conclusion Purpose

Analysis Hypothesis

Apply what you’ve learned…..

• The effect of one minute of walking and one minute of running on the pulse and respiration rates of a human.In this experiment, what is/are the responding variable(s)?

Speed Time

Pulse & Respiration Rates Walking & Running

Apply what you’ve learned…..

• If you were doing research on the deadly E-bola virus, which resource in the library would give the most current information?

Internet Book

World Book Encyclopedia Reader’s Guide

Apply what you’ve learned…..

• The effect of one minute of walking and one minute of running on the pulse and respiration rates of a human.

In this experiment, what is/are the controlled variable(s)?

Speed Time

Pulse & Respiration Rates Walking & Running

Apply what you’ve learned…..

• Scientists must analyze the results of an experiment before they:

Form a hypothesis Perform experiment

Identify a control Draw a conclusion

Apply what you’ve learned

• A student plants one marigold seed into each of three pots. One pot she uses soil from a flower bed outside her house, one pot she plants with soil from a garden store, and one she plants into rocks. She uses a pitcher and waters each seed. She puts a pot on the window sill of her kitchen, one under the grow lights on her porch and one in a bag. She waits three days and makes her first observation.

This is not a well prepared experiment. On a sheet of paper write at least 3 reasons why this is not a scientifically sound experiment. Then we will discuss your answers.

Congratulations! You’re correct!

Congratulations! You’re correct!

Congratulations! You’re correct!

Congratulations! You’re correct!

Congratulations! You’re correct!

Congratulations! You’re correct!

Congratulations! You’re correct!

Sorry, that’s incorrect. Try again.

Sorry, that’s incorrect. Try again.

Sorry, that’s incorrect. Try again.

Sorry, that’s incorrect. Try again.

Sorry, that’s incorrect. Try again.

Sorry, that’s incorrect. Try again.

Sorry, that’s incorrect. Try again.

DISCUSSING…..

Back to the car…again..

• How would we perform the experiment to test our hypothesis ? (If gas is put into the car, it will start.)

• How would we collect and analyze our data?

• If the car starts, what can we conclude?

• If the car doesn’t start, what can we conclude? How could we redesign our experiment to find out why the car won’t start?

Remember! The scientific method is a systematic way to solve a problem or answer a question. It’s a method that can be applied in your daily lives, not just in science class. So try it!!