A few days ago Everett asked me how electricity worked. We were in the car at the time, so I gave him my own - limited - explanation, and told him that we could look it up when we got home (and that he could talk to his Pop, an electrician!)
Yesterday I was putting some things away in a closet, and right in front of me was this:
If I was aware that we had it, I'd completely forgotten about it. I brought it out for him yesterday, and we worked through the first few projects in the book, learning about the loop of electricity, and powering a light, a buzzer, and a little engine. He can't wait for Tegan to take her nap today so we can do some more.