Here are some electricity kits.
If your kids like the Magic Tree House Series- they might enjoy this electricity kit using their favorite characters.
This next kit- I bought for my kids. It is a great product. It comes with a picture book and circuits that kids (ages 5-10 yrs) can follow. My sons love this kit- and there are enough alligator clips for two boys to play at the same time.
I found this set on Amazon. I was tempted to buy it for my sons for Christmas, I like the features.
It looks like a circuit board and has all the components clearly labeled. (The transistors, resistors and capacitors- whatever those mean??/ lol I am not an electrician or electrical engineer.) The reviews say that the directions are easy to follow for 10 year old + kids, but falls short of explaining the functions and why it works. So that is a little disappointing. If you have any working knowledge of electricity and can teach your kids- then this is a great kit.
This last option is what I am personally leaning towards.
This book assumes you know nothing. (Perfect) At Makershed.com they offer a kit with all the parts- for half the exercises described in the book. (Wonderful!)The book walks you through the steps and then if you want to know the why it works... it explains it, using words the average person can understand.