It sounds like your son is lucky to have you in his life.  Before I give you some sugestions of what you might want to try to help your son with his attention, please know that it sounds like your son's activity is normal.  Little boys are known for being on the move.

Since you are homeschooling him, you have more flexibility in scheduling of lessons.  I'm sure you are working with a homeschooling group and they probably have some additional advice they can give you.  

Try to make the lessons as hands on as possible.  For example, if you are studying about insects, take the lesson outside.  Sometimes just the change of scenery can help.

In your school area that you have set up, get rid of the regular chair and have your son sit on a yoga/exercise ball.  Just make surfeit fits his size in relationship to the desk or table his does his work.  By sitting on the ball,his brain is always alert because of the balancing.  At first it will be fun, but keep in mind that the research behind this is that the brain is always active.  It will help to get the wiggles as well.

Have him do the work.  Even teachers have trouble with this one.  Kids are smart and know exactly how to get the adults to do the work.  Instead of asking question, have a discussion.  You can ask question or phrase ideas to stretch your son's thinking.  (withint the next month, my company will have a new product that provides question stems that are inline with the Common Core State Standards - this will be a good tool for parents as well).

A book you may want to check out is called The Daily 5.  Even though it is for teachers you might finding useful, especially since you are homeschooling.  The book describes how to build up stamina in areas and writing.  There is a beahavior component built into this approach.

Once again, your son sounds like a happy seven year old boy.  Please read to him every day.  That is one of the best gift you can give to him.

Hope this helpsor at least gives you something to thing about.

Barb K
Www.LessonPop.com