As a fellow teacher, I find that kids already have some kind of awareness of Bitcoin. Some of their parents may even have bought a Ledger.

To ascertain their current understanding of Bitcoin, I will probably divide the class into groups and get them to just write down all the words that come to their minds when they think of Bitcoin - if your kids are the sort that don’t mind speaking up. When they pull their ideas together, they may find that they actually know more (and have more misconceptions!) about it than they realise. Then, you can assess where their level of knowledge and skills is at and respond accordingly so that they feel that you are adding to their baseline of knowledge.

Also, honestly, Kahoot! quiz works best to assess knowledge and stimulate interest in your students. In another lesson, you could have a True/False Kahoot! quiz to get them fired up xP