Please note that the Indian Springs Trout Farm is closed due to wind damage and required cleanup. Check their calendar page to see if it has reopened/they have time slots available to book.
The Indian Springs Trout Farm in Oregon City is very popular with families. They provide all the tackle needed for a fun fishing experience, plus it's on private property so no fishing licenses are required for older kids and parents. You only pay for fish caught, with prices ranging from $3.50 for eight inch fish on up to $5.40 for 12-inchers. Kids can try their luck fishing for rainbow trout as well as bluegill, catfish and crappie. They're typically open Wed-Sun from 8am-6pm. Visit their Facebook page for complete contact information.
A little south is the Canby Pond in Canby Community Park. Only kids 17 and under can fish here, as well as anyone who holds a Disabled Angler permit from Oregon Department of Fish and Wildlife. The pond is stocked at various points throughout the year depending on conditions. Kids can try for rainbow trout, bass, bluegill and crappie.
If you want to combine fishing with an awesome camping trip, here's all the campsites in Mt. Hood Territory. Good luck out there and remember, a bad day fishing beats a good day working.