An observational study to evaluate the effectiveness of supplementing a reading program with a television show was conducted in several schools in grade 4. Some classroom teachers chose to supplement their reading program with the television show and some teachers chose not to supplement their reading program. Some teachers chose to supplement if they felt that it would help their class improve their reading scores. The study collected data on a large number of student and teacher covariates measured before the teachers chose to supplement or not supplement their reading program. The outcome measure of interest is student reading scores.

a. Describe how this study could have been conducted as a randomized experiment.

b. Is it plausible to assume that supplementing the reading program is ignorable in this observational study?