An instructor hypothesizes that doing jumping jacks will improve his students' quiz performance. On Monday, he has his class sit in their chairs for 5 minutes before completing a multiple-choice quiz on their reading assignment. On Wednesday, he has his class do 2 minutes of jumping jacks before completing the same quiz that they took on Monday. The students performed better on the quiz on Wednesday. Which is a possible threat to internal validity in this study?

Testing

Explanation:

Testing because when you have done something once, you improve on it the second time because you have been exposed to it (exposed to it twice).

Testing

Explanation:

Internal validity can be defined as the approximate truth when it comes to making inferential deductions about casual or cause and effect relationships. In this scenario, the likely threat that would make this hypothesis wrong is that testing, and this is because once something has been done once, there is every tendency that one would improve on it when the same thing is done a second time as a result of being exposed to it twice. Hence the researcher inferring that jumping jacks will improve his students' quiz performance in such scenario might be wrong.

credit card number 4 is the right answer

answer; the federal reserve system;