Loved this book as a kid. It opened up my mind to "new" ideas about science. As a kid it's a Pick, as an Adult re-reading it, Seemed short (I couldn't believe how dense and rich it was in my childhood brain); like some pieces were missing. I could appreciate how ahead of her time she was; however now a bit dated. Although, my son read it about 5th grade (now 19) and felt the same way about it as I did as a 4th or 5th grader. So, still is a Pick!