Keith
I'd be very careful of a 12 year old wading some parts of the Lackawanna. That being said, there are many areas he could safely wade, even fish from shore.
Trophy trout section starts at the Gilmartin St. bridge in Archbald.
Standard nymphing fare will work, as will wooly buggers. Starting to see the occasional little black stone fly here and there.
Where are you located? Feel free to PM me if you like.
Dave