Refer to Exhibit 10-1. The external validity question in this study would be:
a. is vocabulary instruction worth the time it involves?
b. was vocabulary instruction really responsible for the observed difference in reading scores?
c. would vocabulary instruction improve reading scores for all third graders?
d. should the teacher have exposed all the students to vocabulary instruction?
Question 2
Refer to Exhibit 10-1. The control group would be those who
a. are in the class.
b. are willing to cooperate in the research.
c. have a library period.
d. have high grade averages in reading.
e. receive vocabulary instruction.