Threats to Internal validity Decide which spDecide which specific threat(s) are reducing the internal validity of the following examples and provide an explanation for your decision. 2. As part of a course, an instructor has his students take the GREs. The students do not do well. The instructor decides to offer a one-hour session to help his students prepare for the GRE. Afterwards, he has the students take the GRE a second time and finds that their scores have improved. Can we conclude that the one hour prep-session was effective? Why or why not?ecific threat(s) are reducing the internal validity of the following examples and provide an explanation for your decision. A researcher is interested in comparing two different teaching methods. One method is used at school A and the other method is used at school B. During the course of the study, the principal at School B is fired and replaced by a new principal