Based on the profound principle: Slow and steady wins the race
1) Start with manageable steps.
2) Having mastered that step, take a small step forward.
3) Keep moving forward without taking a break... and success is sure to follow.
This app starts out with extremely simple and manageable steps
Day 1: Divide by 1
1/1
2/1
3/1
...
2) Having mastered dividing by one, you move to day 2.
Divide 2/1 to 10/2 (not 2/2 to 20/2). Remember, simple manageable steps.
3) Day 3: 12/2 to 20/2
... you get the drill.
Practice 40 questions a day. You can set the pace for you child using the settings menu. However you can answer no more than 3 questions wrong within the time allotted to move to next day.
On completing a day successfully, you get a checkmark against that day. This helps keep track of progress and provides motivation.
An extremely simple principle indeed!
Yet more effective than any other approach you can take to acquire a new skill.