Overall, this was a good curriculum. It would be nice if there was a Middle School supplement with more advanced activities for older kids who want to go just a bit deeper but are in between the elementary age and high school. I spent a LOT of time researching and coming up with my own activities to make it more interesting for the older crowd.
I thought this textbook was a good introduction to chemistry and physics, but I wouldn't say it is a k-5 book. I'd recommend it for an advanced 4th grader or 5-7 grades. My kids loved the experiments but their eyes glazed over during the readings.