Nice, saw that one in a bookshop (!) recently, wanted to look if it was released to try it but totally forgot about it later.
"Was ist was" is a popular series of books here in Germany, no idea if they ever sold it internationally, aimed at kids, explaining a different scientific topic in each book. I *loved* these books when I was young, I had several dozens of them.
EDIT:
Meh, it's mainly multiple choice questions about very easy general knowledge topics. Nothing to write home about, but might be a nice game for a 8-10 year old.