My 7 year old son is in grade 2. In the previous grade, despite his intelligence, he was significantly behind his class in handwriting, letter reversals, and spelling. He was getting extra help from his teacher, but he still had an uphill battle. So I decided to start a flashcard routine to assist. This solved the original problem. Here is a description of the current routine, and how it has evolved to this point.
It will surprise nobody who has read Teaching Linear Algebra that I started with the thought of some sort of spaced repetition system to maximize his long-term retention with a minimum of effort. I needed to help him with around handwriting, so I wanted to be personally evaluating how he was doing. This seemed simplest with a manual system. I therefore settled on a variation of the Leitner system because that is easy to keep track of by hand.
To make things simple for me to track, I am doing things by powers of 2. Every day we do the whole first pile. Half of the second. A quarter of the third. And so on. (Currently we top out at a 1/256th pile, but are not yet doing any cards from it.) Cards that are done correctly move into the next pile. Those that he get wrong fall into the bad pile, which is the next day’s every day pile.