Notice that I did not write, “If they still don’t get it.” When teaching, it’s important to frame issues not in terms of student understanding, but in terms of your explanation. For example, I’ll often say, “Am I being clear?” as opposed to, “Do you get it?” This places the burden of clarity on me, and students are more likely to volunteer and engage issues if they don’t think that the instructor believes they have a problem understanding the material.