A recent study reports that elementary school students who were given a nutritious breakfast each morning had higher test scores than students who did not receive the breakfast. For this study, what is the independent variable?​

In this study, the independent variable is the provision of a nutritious breakfast to elementary school students. The independent variable is the factor that the researchers are manipulating to see if it causes an effect on something else, which in this case, is represented by the test scores of the students.

Extra: The independent variable is often referred to as the "cause" or the "treatment," it's what you change intentionally to see if there is an effect on another factor. In scientific experiments, the independent variable is manipulated by the researchers. In the context of this study, by providing a nutritious breakfast for one group of students and not providing it to another, the researchers can observe the changes in a dependent variable. The dependent variable is the "effect" or outcome that is being measured. For the study in question, the dependent variable would be the students' test scores. If the researchers find that the students who were given breakfast performed better, they might suggest that having a nutritious breakfast can help improve test scores. However, it should be noted that correlation does not imply causation directly; additional research is often needed to establish a causal relationship between variables.