Inglewood Science Fair
Design an Experiment
Design an experiment to test your hypothesis. You need to determine your variables, constants, materials and procedure.
- Independent variable: What you change.
- Dependent variable: What you measure and observe.
- Constants: What you keep the same.
- Materials: Equipment required to carry out the experiment.
- Procedure: Steps required to carry out the experiment.
Experimental constants are very important! You must keep everything the same for each of your tests EXCEPT the independent variable. Otherwise, you won't be able to tell what caused the outcome of your experiment. Was it the independent variable or some other factor?
You should repeat each test several times to make sure your results are reliable. In the paper towel example below, each brand is tested three times.
Record your measurements in a data table. You will also need to make observations about what you see. Keep the procedure clear, but simple, and NUMBER YOUR STEPS.
Example: Strength of Paper Towels
Materials
- 3 brands of paper towel
- graduated cylinder
- 500 pennies
- testing frame
- water
- masking tape
- blocks of wood or books
- stop watch
Procedure
- Prepare a Data Table.
- Cut three, equal-sized pieces of each kind of paper towel.
- Place one piece of Brand A in a testing frame such as an empty picture frame.
- Tape the towel securely around all edges with masking tape.
- Raise frame 3 inches off the table using blocks or books.
- Pour 10 mL of water near the center of the towel.
- Wait one minute until water absorbs.
- Place pennies one at a time near the middle until a tear occurs or the pennies fall through.
- Record data and make observations in your log book.
- Repeat with all of the nine samples.
Variables & Controls
- Independent variable: brand of paper towel
- Dependent variable: number of pennies that caused a tear in the towel
- Constants: amount of water, temperature of water, size of the towel and frame, distance of the frame from table, wait time for water absorption
Data Table
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