Digital devices (most often laptops and smartphones), though desired tools by students in a higher education classroom, have in the past been shown to serve more as distractors than supporters of learning. One of the reasons is the often undirected nature of the devices' usage. With our work we aim to turn students' digital devices into teaching and communication tools by seamlessly interleaving lecture material and complex questions in the students' browser through ASQ, a Web application for broadcasting and tracking interactive presentations. ASQ's fine-grained logging abilities allow us to track second by second to what extent students are engaging with ASQ which in turn enables insights into student behaviour dynamics. This setup enables us to conduct ``in situ'' experiments. Based on the logs collected in a longitudinal study over a ten week period across 14 lectures with more than 300 students, we investigate (i) to what extent ASQ can be reliably employed to assess attention and learning in the classroom, and (ii) whether different in-class question spacing strategies impact student learning and engagement.