Scientific Method Controls and Variables – Part 1
Patty Power
Mr. Krabbs wants to make Bikini Bottoms a nicer place to live. He has created a new sauce that he thinks will reduce the
indigestion associated with eating crabby patties from the Krusty Krab. He recruits 100 customers with stomach problems.
He has 50 of them (Group A) eat crabby patties with the new sauce. The other 50 (Group B) eat crabby patties with sauce
that looks just like new sauce but is really just mixture of mayonnaise and food coloring. Both groups were told that they
were getting the sauce that would reduce indigestion. Two hours after eating the crabby patties, 30 customers in group A
reported having fewer indigestion problems and 8 customers in group B reported having fewer indigestion problems.
If crabby patties cause gas, then people who eat crabby patties
with the new sauce, will not have as much gas/indigestion.
1. Write the hypothesis.
Group B is the control group-they did not get the
new sauce--(independent variable)
2. Which people are in the control group?
3. What is the independent variable?
4. What is the dependent variable?
the new sauce
the amount of gas/indigestion customers still had
5. Write the conclusion for Mr. Krabbs’ experiment. The
new sauce appears to work since it
reduced the amount of gas/indigestion in 60% of customers being tested. The
hypothesis was supported by the data.
6. Why do you think 8 people in group B reported feeling better?
The customers in group B believed they were eating the new sauce. As a result, they thought
they had less gas/indigestion. This is called the placebo effect.
Slimotosis
Sponge Bob notices that his pal Gary is suffering from slimotosis, which occurs when the shell develops a nasty slime and
gives off a horrible odor. His friend Patrick tells him that rubbing seaweed on the shell is the perfect cure, while Sandy
says that drinking Dr. Kelp will be a better cure. Sponge Bob decides to test this cure by rubbing Gary with seaweed for 1
week and having him drink Dr. Kelp. After a week of treatment, the slime is gone and Gary’s shell smells better.
7. Write the hypothesis.
If snails with slimotosis rub seaweed on their shells and drink Dr. Kelp, then their
slimotosis will be cured.
8. What is the independent variable?
9. What is the dependent variable?
the two cures-seaweed and Dr. Kelp
the amount of slime and odor
10. Write the conclusion for Sponge Bob’s experiment (remember to use data).
Although Gary’s slimotosis symptoms disappeared, it can’t be known for sure which
cure was responsible. The test needs to be repeated using a control group and
other experimental groups for each type of cure. Also, Gary should only have
tried one cure at a time, not both at the same time.
Marshmallow Muscles - Larry was told that a certain muscle cream was the newest best thing on the market and claims to
double a person’s muscle power when used as part of a muscle-building workout. Interested in this product, he buys the
special muscle cream and recruits Patrick and SpongeBob to help him with an experiment. Larry develops a special
marshmallow weight-lifting program for Patrick and SpongeBob. He meets with them once every day for a period of 2
weeks and keeps track of their results. Before each session Patrick’s arms and back are lathered in the muscle cream,while
Sponge Bob’s arms and back are lathered with the regular lotion.
11. Write the hypothesis.
If people use the “special muscle cream”, then their strength will double.
12. Which person is in the control group?
13. What is the independent variable?
14. What is the dependent variable?
SpongeBob
the special muscle cream
(strength) the number of marshmallows that can be
lifted
15. Write the conclusion for Larry’s experiment (remember to use data to determine the conclusion)
Both Patrick and SpongeBob increased their strength. But only Patrick used the
new “special muscle cream”, and his strength did not double. It does not appear
that the muscle cream lived up to its’ claims, If it worked as claimed, Patrick
should have been able to lift 36 marshmallows. So, the hypothesis is rejected.
Microwave Miracle
Patrick believes that fish that eat food exposed to microwaves will become smarter and would be able to swim through a
maze faster. He decides to perform an experiment by placing fish food in a microwave for 20 seconds. He has the fish
swim through a maze and records the time it takes for each one to make it to the end. He feeds the special food to 10 fish
and gives regular food to 10 others. After 1 week, he has the fish swim through the maze again and records the times for
each.
16. Write the hypothesis.
If fish eat food which has been microwaved then they will become smarter than
they were before.
17. Which fish are in the control group?
18. What is the independent variable?
19. What is the dependent variable?
The fish that eat regular food
microwaved food
Smarter fish (the time required to complete the maze)
20. Write the conclusion (remember to use the data to determine the conclusion)
According to the data, all but one fish in each group improved their time through
the maze. The special food does not seem to have been a factor. It is more
likely that the fish went through the maze faster the second time because they
had already done it once and were more familiar with the maze the second time.
In this case, the hypothesis was not supported.