Due to the large amount of missing data (about 53% of students were missing demographic, per- or posttest data), it was not advisable to use multiple imputations to include more of these students and teachers in our analyses. As a result, we compared those participants included to those excluded using x2 tests and t-tests to examine differences in our demographic and pretest variables. We found several differences (see Additional file 1:Table S1). For instance, excluded participants were more likely to be male, African-American or Hispanic/Latino, and to have ELL status. They were also more likely to come from schools with a higher percentage of students receiving free or reduced lunch. There were few significant differences between the groups on student pretest variables, with the one exception being that excluded students had lower self-efficacy than included students (p = .037). There were significant differences between the groups on several teacher pretest variables. The excluded participants had teachers with lower self-efficacy for student engagement and instruction (p = .002) and self-efficacy for technology use (p < .001) than included participants. However, excluded participants had teachers with higher mathematics self-efficacy (p < .001) than included participants. The implications of these differences are examined in the discussion section. The included 7,900 students were approximately equally divided across grade levels (see Table 1). The majority of students (60%) were White, with 23% African-American, 8% Hispanic, and 3% Asian. Four percent of students were identified as English-language learners [ELLs]. School level information was collected about students’ eligibility for free or reduced lunch; participating schools had an average of 34% of students who were eligible for free or reduced lunch, with eligibility at the school level ranging from 2% to 85%. We also collected students’ most recent scores on the state standardized test in mathematics, the Virginia Standards of Learning (VA-SOL) test; this test is given annually to students in grades 3-8