Scouts often show up with knives to "sharpen" that are very, very dull. A two-sided Carborundum (silicon carbide), crock stick (aluminum oxide ceramic), and cardboard for stropping should cover the range of needs.
If you can convince them to keep their knives fairly sharp at all times, you will have done them a good turn. (Good test of "Explain.")
A good teaching prop is a wooden paint stirring stick. They can sharpen it to get the muscle memory in place. Any flat piece of scap metal of suitable size can also be used. Otherwise, Dollar Store knives can be used.
Moving the knife in circles on the sharpening "stone" with the knife blade at the correct angle is easier for kids to master than the method in the Hardbook on p. 404.
The included angle of 60 degrees suggested on p. 404 is fairly dull.
Washing the knife "with the rest of your dishes" as suggest on p. 403 is a terrible idea.
The Handbook assumes that all parts of the knife are impervious to water. That is true only if there is no carbon steel in the knife.
Best of luck.