For each of the following research examples, identify the threat to internal validity that could also explain the improvement in math performance. Because a pretest– posttest design is used and the...

For each of the following research examples, identify the threat to internal validity that could also explain the improvement in math performance. Because a pretest– posttest design is used and the same test is used at both pretest and posttest assessment in many of the examples, there is naturally a potential testing threat. However, there is also another potential threat in each example, and it is this other threat that I want you to identify.