The effect of the time of day a psychology class is taught on test scores is being studied in an experiment. Teacher effectiveness has been identified as
an extraneous factor that could also affect test scores. Students of three
different teachers are included in the study. How can teacher effectiveness
best be addressed to minimize its effect in the experiment?
O A. Replication of the experiment at different times of the year
B. Randomization of students in morning and afternoon classes
C. Direct control of why textbook is used
O D. Blocking into three groups based on the teacher of the class