Teacher behaviors such as providing frequent opportunities to respond and feedback are known to promote student engagement. In addition, contextual variables such as grade-level and instructional grouping may affect engagement. However, less is known about teacher behavior in these instructional contexts. This study aimed to examine active instruction and engagement across elementary, middle, and high schools using a large database of direct classroom observations. Additional analyses were conducted to examine teacher and student variables within and between instructional groupings in elementary schools. Results revealed that whole-group instruction was the most frequently used format regardless of grade level, but individual opportunities to respond and active engagement were significantly higher during small-group lessons. Exploratory analyses of subsets of observations indicated that (a) group size affected frequency and duration of discrete teacher and student behaviors and (b) relationships among variables varied by context.