The National Canal Museum is a great museum for kids. There are plenty of hands on exhibits so that they can understand the physics of water and weight and how it lead to the development of the canal systems in the early 1800s in the United States, There is a complete canal system in the hands on exhibit, Waterworks. Here each person gets a toy canal boat and takes it through a series of locks and dams over a mountain to deliver a load. Be prepared to get wet and learn.
For a 'National' museum, there is very little in the way of artifacts and photos. There is not much on the history of the rise and fall of the canal systems in the United States.