I built my kids an inexpensive fly rod in their favorite colors then showed them how to cast or flip a small bright colored streamer into the pond and told them when a fish grabs it jerk on the line.
Not pretty but they can pick up the specifics and refine their technique if they continue with the sport.
Also take some worms along for backup...you can always put a mealworm on the end of a streamer.
The key is to have fun and if we drill them with techniques and theories it's too much like school.
If they like it they'll ask to learn more and if they don't we'll go swimming next time.