1. Controlled Experiment:
A test that you COMPARE at least 2 groups. You must have control over all factors, to be confident about your results.

2. A Tale of Two Kittens….

3. Jane and Larry are interested in performing an experiment about cats
Jane and Larry are interested in performing an experiment about cats. They already know that humans often enhance their diet with vitamins to improve their health. They want to know if this would work for cats too…

4. QUESTION: HYPOTHESIS: Will adding vitamins to cats’ food
help to improve their health?
HYPOTHESIS:
Jane and Larry both believe that adding vitamins to their cats’ food will improve their health, because adding vitamins to peoples’ diets improves their health.

5. To test their hypothesis, Jane and Larry perform multiple tests…

6. Test #1: + + Cat A eats the vitamin enhanced cat food
Cat B eats the vitamin enhanced cat food. + +

7. (after TEST 1…) RESULTS: Both of the cats’ health improves! Cat B
Cat A

8. CONCLUSION:
According to the results, adding vitamins to cats’ food does improve their health!!
Wait a minute…

9. Test #1: + + Cat A eats the vitamin enhanced cat food
Cat B eats the vitamin enhanced cat food. + +

10. + EXPERIMENTAL GROUP CONTROL GROUP
The group in an experiment that gets the treatment
The group in an experiment that does NOT get the treatment +

11. Test #2: + Kitten A eats the vitamin enhanced cat food
Kitten B eats just cat food. +

12. (after TEST 2…) RESULTS: Kitten B didn’t grow quite as large
Kitten A grew larger
Kitten B didn’t grow quite as large
Kitten B
Kitten A

13. CONCLUSION:
According to the results, the Persian grew bigger and the Siamese didn’t grow as large. Therefore, the vitamins MUST have worked!
Wait a minute…

14. Test #2: + Kitten A eats the vitamin enhanced cat food
Kitten B eats just cat food. +

15. The ONE difference between the 2 groups in an experiment
VARIABLE
The ONE difference between the 2 groups in an experiment +

16. Test #3: + Kitten A eats just cat food.
Kitten B eats the vitamin enhanced cat food +

17. Kitten A is not quite as healthy
(after TEST 3…)
RESULTS:
Kitten B is healthier
Kitten A is not quite as healthy
Kitten B
Kitten A

18. CONCLUSION:
According to the results, the kitten that received the vitamins grew to be healthier. Therefore, the vitamins do in fact help make kittens healthier!

19. CONSTANTS ___________ ___________ ___________
The factors (things) in an experiment that are kept the SAME between the 2 groups +