A couple of the children are just at the right age to love the idea of codes and secret messages and spies. One of them suggested a "Spy Unit," and it was fun to put one together!
Some stuff from the International Spy Museum. I went to a spy museum in Berlin a few years ago (didn't get to take any of the children there, unfortunately, but I showed them pictures!).
We made these spy I.D. badges.
The girls especially really got into these cipher wheels, once they got the hang of them. Here's another version if you'd rather not write your own letters (we had a hard time getting ours to all line up very well).
Why did I put this picture here? I think I knew at one point, when I was putting together this post. But now I can't remember! It was something from our chemistry set—maybe a chemical that is used in invisible ink, or something??
I got some big thick books from a thrift store (Abe was pleased that his was something like A Gentleman's Guide to Wine and Spirits, ha ha) and we made secret caches out of them. You just glue a big hunk of the pages together with white glue (spread it all along the sides of the pages) and then use a utility knife to hollow out a space within the pages. It takes forever but it makes such a cool hiding place! Daisy keeps her code wheel in hers, as well as other TOP SECRET items.