Normally, I use books which advocate a step by step method in order to teach kids, but every kid is different and you can’t apply the same method to all of them. One day I came across the following sentence when I was reading Chess Fundamentals.
“The first thing a student should do, is to familiarize himself with the power of the pieces. This can best be done by learning how to accomplish quickly some of the simple mates.” Capablanca
So why can’t we do just this while teaching tactics to kids? I didn’t see why not and came to the conclusion that the mates in two from Laszlo Polgar’s 5334 Problems, Combination and Games was the best source of material for teaching kids tactics and mating patterns, and without using any jargon! There is also no need to find problem sets for different tactical motifs. One of my students did around 1600 mates in two and was then able to find tactical possibility without learning particular tactical motifs.
As I gained experience in the field of chess coaching, my belief become stronger and stronger that kids should solve more and more checkmate in one move problems before proceeding further. Here you can use Elementary Checkmates I and II that can be found at ChessOK.