Chronicling the struggle to overturn transportation segregation laws, an introduction to a significant time in civil rights history relates the case of Morgan v. Commonwealth of Virginia and discusses the significance of the Freedom Rides.
This is a children's book, but I would say it would be for children 8+. The reading level and subject matter match - there are descriptions of violent acts but they lack the harrowing detail of what civil rights activists endured. I like to read these sorts of books before my children do, and this was an easy and interesting read for me as an adult.