These free word searches based on WW2 can be an excellent teaching resource. Before explaining to them the Allied and Axis powers, you can download and print these word searches to give them a quick insight into the topic. As they search for words like Holocaust, Anne Frank, Gas Mask, you can explain each of them in short.
After you have completed explaining your lesson, you can also use these puzzles to see who has understood it. You can pick up any word and ask anyone to tell about it in a short while they try to find them out.