Problem:
A professor wants to test whether a particular teaching technique is effective in improving achievement in her class. She teaches her morning section using the new teaching method. The afternoon section is taught using the standard method. She compares the two groups on identical achievement tests and finds the students with the new method do better than those taught with the old method.
1) What is Internal Validity?
2) Identify (and define) two threats to internal validity in this study.
3)
4) Describe two things that can be done to improve the internal validity in this study.