One student has spent several weeks deliberately missing the lectures and going only to the computer lab sessions (the lab session was immediately after lectures and I refuse to believe the alarm clock kept failing several weeks in a row, so it must have been deliberate). Once at the practical sessions, this student has been repeatedly asking us practical tutors to explain concepts which were explained at length in the lecture. Replies have been initially along the lines of "Well, if you'd been to the lecture, you'd have had that explained to you in detail", followed by internal deliberation about how much time to devote (or not) to answering the student's question further, given how many other students who did go to the lecture also have queries in the computer lab session. Is it reasonable that a student deliberately pass up the opportunity to hear an explanation of a concept, only to demand extra time afterwards for a repeat opportunity, at the expense of other students? I think not.
Anyway, said student has started going to lectures. At last. A small victory. As for the 25% of students who are not turning up for either lectures or lab sessions(*), though....
(*) Before you wonder, no they are not vile/boring/unhelpful lectures or lab sessions; students who have been to them rate them highly.