Have you tried audio books? Some people comprehend better through listening, and some need to do something else while they are listening.
Maybe he would like to do projects for school work. Incorporating his interests as much as possible into school should help.
With my son he does science naturally as time allows, so I write down what he does, and he shows me his projects and discoveries. He will do formal curriculum for high school science.
Letting him chose a time period in history to study would be good too.
The more choices he gets, the better. The two of you will discover his areas of interest as you go, and hopefully his love of learning will return.
