In a very easy-to-understand fashion, this book explains one type of simple machine to children. Each page has a definition of the more difficult new words (like "friction") that help reinforce the new concepts being taught. I read this book to my 3 1/2 year old twins tonight. While they won't grasp the concepts as well as an older child would, they pointed out the wheels and axels on toy cars, a toy dump truck, and a wagon which proved that they understood more than I would have imagined. I'm now encouraged to read the rest of the series to them to further encourage the never ending thirst for knowledge they have at this age of their lives.

My three year old daughter and I had been observing pelicans on our daily walks. I told her I'd find her a book on them so we could learn more about them. I found this one and bought it. She really enjoys it and while much of the tone of it is above the head of a three year old, she still gets a lot out of it and it will -- likely -- have longevity as she gets older and understands more about it.