Two focusing hypotheses were evaluated. First, do adjunct questions, focusing on science concepts and inserted after computer-animated sequences, selectively alter students' attentional or practice processing and thus produce differential learning effects? Theoretically, such questions selectively focus students' attention and enhance concept learning of focused concepts. Second, do these questions still provide enough metacognitive scaffolding to produce differential learning effects when only the first 8 out of 12 sequences are followed by focusing questions? Eighth-grade students (n = 160) were randomly assigned to a control group (lesson alone) or one of four treatment groups (lesson plus 12 questions focusing either on heat or on temperature, or lesson plus the same first 8 questions on heat or temperature followed by 4 placebo questions). Two significant two-way interactions with widely varying F ratios supported the differential focusing hypotheses (12 questions—more robust interaction, 8—less robust interaction).