Avoid yes/no questions and phrases like "Does this make sense?" In response to these questions, students usually answer "yes". So of course it's surprising when several students later admit that they're lost. To help students grasp ideas in class, ask pointed questions that require students to use their own prior knowledge. For example, when teaching "assumptions" ask students what assumptions they made about writing before beginning this course. Or, ask them what assumptions their parents might make about them. Students' answers to these questions will help you learn whether or not they understand what assumptions are.