The Day We Quit Kumon, Dad Started Building a Math Game

My eldest quit Kumon math. This is not a story about the worksheets being bad. The structure — a fixed amount of practice every day — suits arithmetic well, and while he kept at it, his calculation genuinely improved. The problem was that his enthusiasm wore out first. Once unfinished worksheets start piling up on the desk, they stop being study and start being debt. After watching him pick up his pencil with the face of someone repaying a loan, we decided to stop.

Quitting left a different problem behind. Arithmetic is not a matter of understanding but of automation, and it dulls exactly as fast as you rest. Ending the worksheets could not mean ending the practice. The method had to change.

Keep the Repetition, Change the Reward

What the worksheets did well was daily repetition; what my son struggled with was the pile of work to get through. So I decided to keep the repetition and replace only the reward structure. Conveniently, his dad builds apps for a living — the tool could be homemade.

The first version was never meant for the store. The app icon and the pictures that appeared for correct answers were all photos of my son. The name was an afterthought. An app with exactly one user in the world — and that one user took it surprisingly seriously.

Watching him play from the side taught me a few things.

• Ten problems per round was the right amount. When the end is in sight, starting feels light. It looks like less than one worksheet page, but once “just one more round” kicks in, he ends up solving more.
• Records beat stickers. Solve well and a best score remains; yesterday’s self becomes today’s opponent. Nobody has to tell him to go back in and beat it.
• Even failure needs rules. I gave him three hearts, and the round ends when they run out. Unlimited mistakes kill the tension; ending on a single mistake feels unfair.

That is also when I added the conceit of catching one monster for every correct answer. From a child’s point of view this is not arithmetic practice — it is a monster hunt, and solving problems merely happens to be how you hunt. It sounds backwards, but he solved more problems this way than he ever did repaying his worksheet debt.

From a Personal App to a Released One

After we had used it that way for a while, it occurred to me that there was no reason this structure should only work in our house. I swapped my son’s photos for monster art, organized the math into four operations — addition, subtraction, multiplication, division — across three difficulty levels, and released it as Math Monsters.

I kept two principles while building it. One: no ads — the moment an ad interrupts a child’s screen, it is finished as a practice tool. Two: the basics stay free — addition and subtraction on easy are open to everyone, and the other operations unlock only if and when you need them.

• Google Play: https://play.google.com/store/apps/details?id=com.fadongkwon.math_monsters
• Apps in Toss: https://fadongkwon.com/toss/math-monsters/ — open it on your phone and it connects straight into the Toss app.

It Was Never Worksheets vs. Apps

To head off a misunderstanding: the conclusion of this story is not “apps instead of Kumon.” Plenty of children thrive on worksheets, and an app forced on a child turns into debt just the same. The essence is daily, short, and the child coming back on their own — in our house that shape just happened to be a game. Why arithmetic practice works better in short daily doses is a separate post: Why 10 Minutes a Day Beats 30 in Elementary Arithmetic.

My eldest still brags now and then that he was this app’s “original monster.” Though he is a little sad his photo is no longer the icon.

Other stories from shipping apps after work are in What I Learned Releasing 8 Apps as a Solo Developer. I post updates here and on Instagram (@fadongkwon.soft).