In order to understand the effectiveness of offering free supplemental education on college campuses, students were asked how frequently they went to the supplemental education and their final grades. On average, the more time the students spent at attending supplemental education, the worse their grades were.

1. If X is supplemental education and Y is final grade, explain what X causes Y would look like. First, fill in the correct variable names in the statement “X causes Y”. Then come up with a plausible explanation for how this could be happening.

2. If X is supplemental education and Y is final grade, explain what Y causes X would look like. First, fill in the correct variable names in the statement “Y causes X”. Then come up with a plausible explanation for how this could be happening.

3. If X is supplemental education and Y is final grade, explain what a third variable causes both X and Y would look like. First, fill in the correct variable names in the statement “a third variable causes both X and Y”. Then come up with a plausible explanation for how this could be happening.