Because Quarto seriously has the most interesting titles.
(And they keep offering to send me review copies... and how can I turn that down when they're so cool? So, yes, these were received for review.)
Math Lab for Kids by Rebecca Rapoport and JA Yoder
My kids think this is SO COOL. Packed with math activities that are so fun they don't feel like lessons. Granted, my kids love math (they're freakish that way.... I blame their father) but these are awesome so I'd imagine even kids who do not love math will still enjoy this one. You could use it to sneak some math into your kids' summer. I'll never tell.
Build A.... Butterfly or T-Rex
(Your choice, but they are separate books, lol)
by KiKi Ljung
These are more like cardboard models with some text. The pieces fit into spots on each page. There's not a ton of text, but there is good info and the models look pretty darn cool.
Under the Sea
In The Jungle
both by Paul Boston
These are so cool, but be aware they are a bit more complicated. You navigate through the book using map and math skills. Unlike Math Lab, it's not so sneaky that that's what you're doing, but it makes for an interesting activity. Kind of like an RPG video game but all old-school and paper-y.