This is a great activity for individuals or small groups. You can find plenty of free ones online that cover nearly every subject area, but it’s actually fun (and pretty easy) to create your own.
Creating your own allows you to make it more customized for your class. If your students are older, you can even have them attempt to create one for the rest of the class to solve!
There are many ways to run this reward !
You can even give points to students as they participate.