Just read through this with a 6 year-old who has had it read many times and made the machines and could tell me how all the parts work, explaining gears and axels and pulleys. It does a great job of letting girls be as girly as they like and simply not letting their be any conflict between that and wearing a construction belt (if they like) and making machines for fun and problem solving. I've watched this little girl make her own pulley systems with materials on hand out in the yard casually because it was simply the obvious solution to whatever problem she was having.
What the previous reviewer said, instructions as storybook. decent instructions kind of boring book. My daughter really enjoyed it though, and as much as I don't love them does enjoy the Goldie blox kit as well.