In this paper we investigate teaching with a classroom response system in introductory physics with
emphasis on two issues. First, we discuss retention between question rounds and the reasons why
students avoid answering the question a second time. A question with declining response rate was
followed by a question addressing the student reasons for not answering. We find that there appear
to be several reasons for the observed decline, and that the students need to be reminded. We argue
that small drops are unimportant as the process appears to work despite the drops. Second, we
discuss the dynamics of learning in a concept-sequence in electromagnetism, where a majority of the
students, despite poor statistics in a first round, manage to answer a followup question correctly.
In addition, we analyse the response times for both situations to connect with research on student
reasoning on situations with misconception-like answers. From the combination of the answer flows
and respon…