Saying “I didn’t do the reading” is better than bluffing through a discussion everyone can see through.

Everybody in the room can tell. Bluffing in a discussion produces vague sentences that never get past the title, and both the teacher and the people who did read it recognise the shape immediately, which costs more than the admission would have. You also spend the whole hour braced instead of learning anything.

Say it at the start, quietly, and then listen properly and ask one real question. You will leave with more than the bluffers do. Teachers overwhelmingly prefer the person who says it straight and stays in the conversation.