That's awesome, getting them hooked young! Everyone tells you to keep it simple, but here is the non-obvious advice I learned the hard way:
- Forget fancy lures, get a tub of PowerBait or just plain old hot dogs sliced small. You aren't teaching them technique, you're teaching them that fishing works. Get them on easy, hungry bluegill or sunfish that bite immediately.
- Also bring three rods, One for you, one for the kid, and a third fully baited extra rod ready to cast immediately. When your child inevitably loses their patience, or you get a bird's nest, you can hand them the ready-to-fish pole and keep the action going
- Finally, bring a small, separate bucket for collecting. A five-year-old only fishes for about 15 minutes. The rest of the time, they are collecting cool rocks, pinecones, or leaves. Let them, and they'll consider the trip a massive success, regardless of the fish count.
Good luck!