Scientific method the steps scientists use to create explanations based on the evidence they gather Hypothesis A simple statement predicting the result of a controlled scientific experiment. Scientific method the steps scientists use to create explanations based on the evidence they gather Observation to use of your senses to gather quantitative or qualitative information Independent Variable part of an experiment that the experimenter changes. Dependent Variable changes as a result of the changes in the Independent Variable. Qualitative Observations observations made by the 5 senses. (seeing, feeling, touching, smelling, tasting.) Control a standard to compare with the results in an experiment. sample size The number of subjects used in an experiment or study. Generally, the larger the better.

1. The following is an imPURRfect way to
• think about the scientific method.

2. Josie got two new kittens.
They were identical twins.

3. Josie is a mad scientist
• She decided to conduct an experiment with the two cats.
• In the experiment the control cat (Cat A) would have
• Six ounces of water daily.
• Six ounces of dry food daily.
• The room would be kept at a constant 75 degrees F. and 50%
humidity.
• The test cat (Cat B) would have all of this plus:
• Four ounces of canned or wet food added to his diet daily.
• The independent variable is the wet cat food.

4. Vocabulary
• Qualitative Observations
• observations made by the 5 senses. (seeing, feeling, touching, smelling, tasting.)
• Control
• a standard to compare with the results in an experiment.
• Sample size
• The number of subjects used in an experiment or study. Generally, the larger the
better.
• Observation
• to use of your senses to gather quantitative or qualitative information

5. • Scientific method
• the steps scientists use to create explanations based on the evidence they gather
• Hypothesis
• A simple statement predicting the result of a controlled scientific experiment.
•
• Scientific method
• the steps scientists use to create explanations based on the evidence they gather
•
• Independent Variable
• part of an experiment that the experimenter changes.
• Dependent Variable
• changes as a result of the changes in the Independent Variable.

6. The experiment would be to determine if adding wet food would make a difference in cat growth.
What would happen if you had two cats and everything was the same except for the addition of wet
(canned) cat food?
Control Cat is Cat A.
• He will get everything except for
the test item.
The test cat is cat B.
• He will get everything just like
cat A, and will have wet food
added to his diet.
• The independent variable is the
wet food.

7. About those variables…
• The dependent variable is the amount of growth in the cats.
• We hypothesize that growth may be dependent on amount and type
of food the cats are given.
• The comparison will be to measure the difference in growth between
the control cat (A) and the experimental cat (B) which is the one that
gets the different treatment (The additional food).
• The independent variable is the thing that is manipulated to see what
changes (the addition of wet food for cat B).

8. Every day both kittens were given the same
amount of dry food.

9. Each kitten got the same amount of water
each day.

10. The temperature and humidity was the same
for both kittens.

11. What was different?
The independent variable was the wet cat food.
Cat A never got any wet cat food.
Cat B was given moist cat food.

12. How did the kitties grow? Remember, what we are
measuring for change is growth in the two cats.
Cat A had only dry food. Cat B had both wet and dry food.

13. The dependent variable was the growth of
the cats.

14. Controls:
Same amount of water. Same temperature and humidity.
Same amount of dry cat food.
Different: one cat got wet food added to his diet.
CONCLUSION:
Control cat
Cat A did not eat wet cat food.
• Cat A grew, but not as much as
Cat B
Test cat
Cat B had all things the same but also got wet cat food.
• Cat B was given more food, thus
he grew bigger than the control
cat.

15. No cats were harmed in the making of this
fictional experiment.