As a general rule, the attention span of boys tends to be shorter than that of girls. Obviously, this varies with each child. Depending on personality, boys are usually downright full of energy and constant motion unless they are ill. It helps to understand that this is not abnormal, most of the time.
Even boys who have wonderful powers of focus still have a tendency to bounce, fiddle with objects, look around, and generally want to be on the move. Sadly, boys are often ‘diagnosed’ with ADHD when they are just being boys.
Fortunately, it is possible to promote a healthy environment for your boys which will be more conducive for learning, if you are homeschooling (or not) and can control some of these lifestyle choices.