Approximately 450 first-year general chemistry students across 18 classrooms in a multiculturally
diverse metropolitan region of the East Coast composed the subject population for the
study. There were 7 treatment classrooms and 11 control classrooms from which all data were
collected. The participating teachers’ range of experience varied from novice to master; however,
an overall matched teaching population was found in the control and treatment subgroups.
All the participating teachers were deemed to be successful science teachers in their district and
were selected randomly from a pool of teachers who are active within their professional community.
In addition, the student groups were shown to have equal prior knowledge of chemistry
through their pretest performance on the High School Subjects Test: Chemistry, shown in
Table 1.