We use Math U See... the kids liked it, along with lots of repetition... (i.e ~ Spectrum workbooks..) I just keep hammering ideas at them until they get it... we may drop it for a week or so, to give them time away, then try again for awhile... After awhile, he'll get it. Another thing that helped my daughter, was figuring out how she thinks, and teaching it in a way she could understand... My kids are only in 1st and 4th, so I am not sure what to tell you for the older grades... Good luck...