How could learning tools help students practice explaining a topic?

A student might finish a lesson and do well on practice questions, then struggle when asked to explain the same idea aloud.

Understanding something privately and presenting it to others seem like different skills.

For people who have built or used education tools: have you found a way to help with that step?
Would you use a short spoken explanation, audience questions, peer feedback, or something else to help a student practice?

I’m especially curious how you would tell whether a student understands the topic better, rather than has simply memorised a polished answer.