Quick note about worksheets: People sometimes ask me where I get my worksheets. I prefer to make them by hand using ChessBase. Usually I use rhetorical questions so they are very easy to solve. When it comes to making tactic and checkmate puzzles, I get the puzzles from famous games. If a student's goal is to do thousands of puzzles, I usually recommend software or websites. Although it uses a lot of paper and is more time-consuming, I find that doing things with pen/pencil and paper is a fun and relaxing way to learn. I recommend using this traditional method along with using training software or websites.