As the lesson begins, I tell my students to listen carefully because I'll expect them to teach me after I'm done teaching them. Then, once the basic concepts are presented, we switch roles. I become the student, and the student becomes the teacher.
When students are expected to teach, they become much more attentive during the lesson. Concepts become important to them. Why? Because they'll quickly learn that you won't allow them to repeat, parrot-like, facts and stock answers. The moment that they attempt to present information without understanding the underlying concepts, they'll stumble, especially when you begin asking them questions about the material.
Understanding the concepts allows students to derive new information from the information they have been given. Therefore, if they truly grasp the lesson's essentials, they should be able to answer questions that require them to correlate the material with other things they've learned.
For instance, suppose you present a lesson on the workings of a constant-speed propeller on a typical single-engine airplane. Surely you'll emphasize how oil pressure causes the propeller blades to take a bigger bite of air. No doubt you'll also mention that these same propeller blades have a flat-pitch, default bias (caused either by spring loading or centrifugal force).
Now it's your student's turn. Let your student teach you the same concept. Then ask him or her what it means when, during climbout, the propeller's speed suddenly increases from a preset climb rpm to redline without movement of the prop control. That's a fair question, and it tests a student's understanding of the lesson's most important concept. (The answer you're looking for is: the prop governor has failed or the airplane is losing engine oil.)
You can apply the I teach you; you teach me principle on the ground or in the air. It works for both primary and advanced students. It's my favorite technique. Hopefully, you'll find it to be useful too.