Non-fiction ideas for curious 4-5 year olds?

[PourquoiTuGachesTaVie]

I'm putting together a list of present suggestions for relatives to choose from and thought some really good non-fiction would be a good idea as ds is asking lots of questions on a wide range of subjects at the moment (the body, technology, history/time being the most common themes at the moment).

What are the non-fiction books your children love?

The Usbourne ones with flaps. My DS2 adores them and comes out with lots of facts.

And there's another range with flaps that I cannot recall and I cannot find one of the books (think they are in car as he reads a lot in the car).

Also the National Geographic do a kids range, some are with Angry Birds which is an extra delight for my son. They do a good space one.