Infodumping, done wrong?

I've just started reading a science fiction novel by a very successful author who will go unnamed. The first fifty pages are pretty infodumpy. That's fine -- you often need to explain how stuff works in science fiction books. The trick is finding a way to do so that makes sense at the time, so it doesn't really feel like infodumping.

So a scientist in the book just said the following, talking about a genetically engineered organism:

"The temperature they encounter outside means they don't have a particularly fast metabolism, which makes their physical motion correspondingly slow. Their blood is based on glycerol so they can keep moving through the coldest ground without freezing solid."

The problem I'm having here is that she was talking to a group of kids aged nine to twelve. Not savants, either, just ordinary kids. It's been a long time since I was twelve years old, but I feel like those sentences would have been pretty meaningless to me back then.

Am I underestimating your average nine to twelve year old, do you think? Or just overestimating the average scientist's ability to talk to them?