With kids, start out with easy fish to catch and don't expect too much. Keep it simple, kids just want to have a fish on the end of the line.
Depending on your lakes or river try these three.
Carp at a current break: A 4 or 6 hook with a couple kernals of corn threaded on. Look for smooth water next to a riffle. Carp suck up the food as it comes into the eddy.
Catfish: Best in the evening: Purchase the stink bait and the fluted tube worms with hook made for paste baits, to paste it onto. Use half to 1oz. slip sinker. Put it above a barrel swivel to stop it from going down to your bait, so the fish feels no drag. Let em run a few seconds. You'll get a feel for the need of a quick set or longer.
Bass: Start out with live bait. Buy some night crawlers, frogs or crayfish, tip them with a #6 hook and toss them out with a split shot. Bass feed the banks, you'll catch bluegill this way too. No more weight than you need, ever. If you go over a quarter ounce use a slip sinker. Don't expect kids to cast a lot until their ready.
Get them an inexpensive closed face reel and a Rhino Rod or Ugly Stick so you don't have breakage. Put a can in the yard and have them cast to it with a practice plug. They'll love it getting ready to go fishin.
Look at my sight for some other tips and tricks.
Good Luck and Good Fishing.