Control group (also called a control)
In each study, there should be one experimental group that does not have the y-variable applied to it
For example, if you are testing whether food dye affects cooking temperature, your control group would not have any dye added
Controlled variables
Controlled variables are elements of the experiment that you keep consistent in all of the trials. They have the potential to affect the results, but since you should only test one variable at a time, they should not change with each trial.
Common examples that may (or may not) apply to your project
Air temperature
Air humidity
Time
Ex: Each trial only runs for 30 seconds
Light
Materials
Quantities
An alternate hypothesis is a statement of your expected results for the experiment; this usually states a difference will occur when the x-value is changed. The hypothesis is a fact-based, expected prediction of what will happen that the experiment will test.
Example: If eggs soak in three dilutions of a sugary soft-drink (low, medium, and high dilutions) for 48 hours, then there will be higher differences in pigmentation in the egg soaked with high dilutions of the soft-drink as compared to the other experimental groups.
A null hypothesis essentially states the opposite of your hypothesis; it often implies that no difference will occur when your x-variable is changed.
Example: If eggs soak in three dilutions of a sugary soft-drink (low, medium, and high dilutions) for 48 hours, then there will be no changes in pigmentation between the eggs in the soft-drinks and the control.
It is good practice to write your variables in the following format: If [y-variable is changed], then [x-variable will happen].
Example: If Pisum sativum plants are grown with low, medium, and high levels of sunlight, then the plants grown with high levels of sunlight will grow the tallest.