What it teaches
How a letter is written, which is not the same as what it looks like. Where the pencil goes down, which way it travels, and how many times it comes off the paper.
Those three things are what handwriting teaching is almost entirely about, and they are invisible in a finished letter. A child who writes o clockwise produces the same mark on the page as a child who writes it anticlockwise, and will be slower at everything that involves a pencil for the next four years.
How it works
The letter appears greyed out on four writing lines, with a green dot where the pencil starts. The child traces it with a finger or the mouse. Finish the stroke and it inks in; a letter with two or three strokes lights up the next one.
A trace that goes the right way but wobbles is accepted, because a five-year-old wobbles. A trace that goes the wrong way round is not, even when it leaves exactly the right shape behind — that is the whole reason the game exists.
Show me runs a pencil along the stroke and says the teacher's sentence out loud: "Round, up, and straight down." After three failed tries it offers that by itself.
What to look for
Three levels: small letters, capitals, then the digits. Small letters come first on purpose — they are harder, and they are what nearly everything a child reads is made of. Starting a child on capitals is a habit school spends a year undoing.
It works best on a tablet or a phone with a finger. A mouse is fine and a trackpad is the worst of the three, which is worth knowing before deciding that a child cannot do it.
Three letters finish a round and earn a sticker. Nothing is timed.