Scientists have found that it's always best to have a control group. Why? Let's say you are measuring whether drinking soda make
s people smarter. You get a bunch of kids who don't drink soda, and give them a test. Then you have them drink lots of soda for a few weeks and have them take a similar test. You notice that their scores have gone up. Wow, did you just prove that soda makes you smarter? Not exactly. It could be that those kids had been studying on their own, or learning stuff in school that helped them on the test. A better experiment has a control group. In this case, it would be a second group of kids from the same place whom you test but who don't drink the soda. If their scores don't go up, then you've just figured out that soda is the real cause. Which of these would provide the best evidence that drinking soda makes people smarter?
A
The soda-drinking group does not show improved scores while the control group does.
B
The control group’s scores do not improve while the soda-drinking group’s scores do.
C
Both the control and soda-drinking groups scored exactly the same on the second test.
D
The control group scored higher than the soda-drinking group on the first test.
