Final answer:
The independent variable in an experiment to see if eating breakfast increases concentration on math assignments is eating breakfast. It is manipulated to observe its effects on concentration or math scores, with a control group used to achieve reliable results.
Step-by-step explanation:
In an experiment designed to see if eating breakfast increases concentration on math assignments, the independent variable is eating breakfast. This is the variable that is manipulated or controlled in order to observe its effect on the dependent variable, which, in this case, would be concentration on math assignments or math scores. To investigate this, researchers might use observation to note that individuals may perform better when they have eaten breakfast. Then, they could design an experimental study with a control group to test this hypothesis rigorously. It is crucial to control other variables to ensure any observed change in the dependent variable is primarily due to the manipulation of the independent variable.