If you are going to be paddling in an area where the current is strong enough to carry your child away from you faster than you can swim while holding on to a paddle and dragging a canoe or kayak by it s painter line, you probably should not take your child paddling in those particular sets of conditions. You can build arguments about swimming after them, and your child is smarter and more level headed then that. The fact still remains that you will never know how your child will react in that situation. Practicing with your child to catch a throw bag or throwable PFD in a swimming pool is an excellent drill. You should never take a child paddling if they have no swimming ability at all.
Children become bored very quickly.
Any person who has been a passive third party during a paddling trip knows that sitting in the third seat of a canoe and doing, nothing, is akin to solitary confinement in the outdoors. There are a number of things you can do to keep active bodies and minds interested in paddling. Try to make the route interesting, stopping on sandbars and islands on the way adds to a special sense of interest on a canoe trip. Even young children can appreciate a remote location that is difficult to get to, and the adults will appreciate the, wow, we must be the only people who have ever been here, comments. Children also enjoy moderate thrills.