Are they basically just scrapbooks on a particular topic?
I've tried to look into them on the web, but I keep getting lots of links where people want to sell me expensive packs and resources and generally pay money.
My kids are a bit young yet, but from what I can gather, you buy a big book and stick in pictures and writing on your topic, either self-drawn/written or downloaded and printed out.
Is this roughly the right idea? TIA.