The reasons why I think this is often not the best question: 1. It's leading - it pushes towards a yes (and silence is interpreted as "yes" - lots of false positives) 2. It's often used as a classic signal for "I want to move on [and don't necessarily actually care about whether or not you have questions]" - particularly because the absence of questions is often followed up with "Okay, great"!, putting anybody who wants to ask a question in the position of being an irritation / barrier 3. Even if it were not for the fact that it applies strong pressure on students to not say anything, students are not good judges of their own understanding - e.g. classic case in coding of a student who watches a YouTube video, tells you confidently that they understand it, but cannot reproduce anything from the video