The website, Animated Knots by Grog, provides several pages of useful knots by activity, along with animated illustrations of how to tie each knot.
The US Search and Rescue Task Force also has a useful webpage on ropes and knots. This page is useful as a quick reference or basic review, once one has already learned the knot.
This video, "Six Knots You Need to Know," is interesting, but is perhaps most useful as a quick way to get to the knot tying videos on YouTube.
All dangerous children should learn basic first aid and basic rescue techniques by the age of 10. Knot tying is a basic part of rescue skills. The first knot that children tend to learn to tie is the bow knot when tying a shoe. But the bow knot is actually a very poor knot for tying the shoe, since it comes untied so easily by accident, sometimes leading to accidents. A better way of tying one's shoe is by one of the variations of the Ian knot. The sooner the child learns such superior knots, the better off he will be in even the most ordinary situations.
This might be a good time to clarify simple terminology. Some readers assume that a "dangerous child" will be a violent child, and that teaching a child to be dangerous is the same as teaching the child to be violent. But that would be a basic misapprehension of the intent here.
The "Al Fin Dangerous Child (AFDC)" is dangerous mainly to those who want to confine and control him, to abridge his rights in some way that is convenient to them, but unjust to the child. To everyone else, the AFDC is a lifesaver and a fount of useful and creative ideas.
The AFDC is nothing if not skillfully versatile, and generally competent all around. But different skills need to be taught at different stages in development. Many skill require the prior mastery of other skills, to be mastered in their turn. And since each child is different in terms of strengths and interests, teaching a child to be maximally dangerous, in the Al Fin sense, requires some delicate loom work and knot tying in itself. Stay tuned.