This article examines how question-answer sequences are constructed in primary school instructional activities. The interaction between teacher and students in two 3rd-year groups is analyzed using a conversation-analytic approach. Four questioning patterns--"yes-no, alternative, wh-questions", and a "non-interrogative format" very frequently used in this setting which I call the "Eliciting Completion Device" (ECD)--teachers use to address the class as a whole are examined in relation to their sequential uptakes: in-unison answers and bids to answer. The analysis shows that students recognize the conventions of question construction as methodical practices used by teachers to convey expectations as to whether the answer is accessible to students. Choral responses are produced when the question is constructed as eliciting information which is obviously known to students, while bids to answer are deployed when the answer is less transparent. The findings reveal that the practices used to construct collectively assembled knowledge are closely connected to the organization of the classroom social order.