A professor is interested in studying how cramming the night before an exam (also known as massed practice) compares with studying over the course of the week (also known as distributed practice). She instructs her students to study for 3 hours without stopping the night before exam 1. She then instructs them to study for one hour each night for four days prior to exam 2, and compares the exam scores. She finds that students who used distributed practice did significantly better on the exam than when student students used massed practice. 1. What is the confound?
2. How could the confound be fixed?