This is a pretty good way to get kids interested in science and explain how inventions evolve, as well as just to get their interest. Each little chapter (each on a different invention or type of invention) runs through things in chronological order, then adds some trivia in a bulleted list at the end. I will say that while Amazon lists it as appropriate for grades 3-7, I would agree with the blurbs that place it starting more at the 4th grade level. Third grade students could probably understand it with some support and would really enjoy pieces of it, but a lot of the vocabulary is more appropriate for many 4th or 5th/6th grade levels. I actually read excerpts to my 2nd/3rd grade students and they really enjoyed it, but I had to change some words and skip some pieces to help them understand.