Simple experiments with easily available materials explain the theory of probability and how it is used by scientists, poll-takers, and industrialists.
After reading a couple of books in this series, I think in general I find them to be too academic/textbook-ish. (That said, if I come across either graph theory/networks one, I will definitely read it.) They can also feel quite outdated at this point, 50-ish years later.
In this one that was especially a problem for me. It talked early on about probability as something used in meteorology (true! and a place where a lot of kids hear/see probabilities!), but it talked about weathermen (sigh) basing forecasts probabilistically off of historical information. That's really, really not how things work now.
Includes some good games/models to introduce probability ideas, though tossing tacks is a weird choice, but nothing too novel. It does get pretty deep into things -- what you expect in general, natural variability, distributions of outcomes, sampling and polling. So there's a lot that's good! But I think, like other books in this series, you have to treat the book very academically, as something to work through.
This was a good book to teach 3-5th graders about probability. I could use this book in a math lesson with my students and incorporate some examples like how many green marbles are in the bag.