Nudity in children's books strange?

So, I'm not sure if this is weird or not, but I was just remembering back in the 'good ol'days' of grammar school, in our kindergartan class had a picture book of illustrations of naked children about our age, like little kids, doing regular little kid things, except they were all naked. like i remeber seeing a little boy jumping out of the sandbox and a detailed illustration of his frontal. it wasnt an anatomy book, just a childrens book.. is that strange and did anyone else have that ?