An educated guess
When you use a control group you don't need a large sample size.
When you have a control group you don't have to do any calculations.
Control groups allow you to compare those recieving the variable and those that are not.
Thickness of the candle
Length of time the candle burned
Color of the candle
She tested too many variables at once.
She did not test a large enough sample of people.
She did not control all of the variables.
If Stride is chewed, then most kids will like it.
If Hubba Bubba is chewed, then the flavor will last the longest.
If Big red is chewed, then it will have the smallest bubble.
Amount of water
Growth of corn
Type of fertilizer
Number of times gum is chewed
Brand of bubble gum
Size of bubble
A change over long periods of time
Keeping things the same
The same thing as evolution