A friend told us about White Moutain Puzzles and we recently bought the American History puzzle. Six of the children are busy working on it, much faster and with more obsession than I would have preferred. I was hoping it would last a while but 'many hands make light work'. It has been great fun, except when I have to tell them to stop and get to work! :)
We also bought the American Revolution but we are saving that for next year when the boys study that time period with Ambleside Year 4. I had forgotten how nice it is to have a puzzle in process and see everyone work on it from time to time. The nice thing about these puzzles is that you are learning about the topic while you work the puzzle. We plan on adding to our collection over the years and maybe keeping a puzzle going all the time.