To conduct a scientific investigation, care must be taken to follow experimental procedures. You must design an experiment to test your hypothesis. When planning your experiment remember to:
- Keep everything the same except for the single variable being tested. A variable is something that can be changed in the experiment. It is what you are testing. Everything else must be the same and only one variable or condition is altered or changed.
- A control group should be used when conducting an experiment. This group receives the same attention as the test groups, however, it will not be influenced by the variable the other groups are testing.
QUESTION: How will the amount of fertilizer used affect plant growth?
HYPOTHESIS: Increased dosages of fertilized will cause greater growth in tomato plants.
TEST VARIABLE: The amount of fertilizer used.
TEST CONSTANTS:
- The seeds must all come from the same package.
- All seeds must be planted in the same sized pots with similar soil.
- All plants must receive exactly the same amount of water and light.
- The temperature should be the same for all test plants.
- More than one plant should be used in each test group (in case one type of seed grows better at this time of year than another).
- More than one seed should be placed in each container (in case one seed is damaged).
- Set one group as the CONTROL GROUP. This group is not given fertilizer.
- Set up two other test groups. Once receives a certain amount of fertilizer and the other receives twice as much.
CONCLUSION:
Which plant group grew the most? Why or why not? What would
you do differently next time?