If he's in that Magic Tree House series-mood, there's several other series that are just a slight step up and might appeal, while getting him more willing to branch out a bit. Magic School Bus chapter books (not picture), A to Z mysteries (yes, there's 26 of them), and Jigsaw Jones mysteries come to mind. These are probably easily found at most libraries; the first two can usually also be bought in bulk via Scholastic.
Thanks for these recommendations. DS6 read every MTH we could find; he's now halfway through A to Z Mysteries and will probably be done by mid-June. I'll get him Magic School Bus chapter books and Jigsaw Jones next. Appreciate it.
