After the students have solved a few puzzles, a very interesting exercise for them is to have teams or two or three generate their own Kenken puzzles and then have the teams exchange those puzzles with other teams who will then attempt to solve them (or to prove that they either can't be solved, or that there are multiple solutions). One way to do this is to have each team draw their puzzle on the board, and then swap the teams around so that students can try to solve the puzzles created by others. This can be fairly time-consuming, and there can be problems with non-uniqueness of the solutions, as well as errors, both by the creators and by the solvers of the puzzles. As was the case with the initial introduction of Kenken to the class, it's probably best just to have the kids try to make some puzzles, and then, after they've seen what some of the problems are, you can make lists of strategies that are useful for puzzle creation. I recommend that the first puzzles that the teams try to create be 4 × 4. Be sure to tell the class that it is important that the puzzles created not only have a solution, but that solution be unique. The author of this article does not claim to be an expert in Kenken puzzle creation (although his software was used to create and check all the examples used here). Thus it may be possible that many interesting ideas are omitted in what follows.