Identify the threats to internal validity in each of the
following experimental studies:
a. At the beginning of the school year, an elementary
teacher set up reading stations in her room with supplementary reading
materials in each. At the end of the year, she reported that the interest of
her class in reading was higher than in any of her previous classes. She
recommended that all teachers set up reading stations.
b. A researcher wanted to investigate the effectiveness of
new teaching materials designed to increase students’ verbal skills. One class
used the new materials, and another class used conventional workbooks. Both
classes were given a test of verbal skills at the end of the semester.
c. A study was conducted in three thirdgrade classrooms
investigating the effect of three methods of teaching math. The teacher could
choose the method she wanted to use but could use only one method with her
students. At the end of the semester, all the third-graders were given the same
math achievement test.
Leave a Reply