Three tools for teaching kids math

Numbers

Place value is the first genuinely abstract idea a kid meets in math. These three tools attack it from different angles: watch a number grow, hold it in your hands, and see that it scales.

Each one is a single HTML file with no dependencies and no build step. They work offline, they remember where you left off, and you can read the whole thing with view-source.

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The Counter
A split-flap airport board that ticks upward. Set the pace and watch it climb. Every time the number crosses into a new place it grows a whole new digit, so a kid sees exactly where 999 turns into 1,000. Each column is labelled with its value: 1, 10, 100, 1,000.
Teaches · counting, digits, rollover
$100
$10
$1
The Money
Type a dollar amount and watch it break into the actual bills that make it. 342 becomes three hundreds, four tens, and two ones, stacked and counted, with the equation spelled out underneath. Hover any stack to fan it apart.
Teaches · place value you can count
2+ 3= 5
20+ 30= 50
200+ 300= 500
The Scale
A kid who can answer 2 + 3 will stall on 200 + 300, as though it were a harder problem. It is not. Slide the scale from ones to millions and the digits never change, only the zeros. Same math, bigger numbers.
Teaches · scale, zeros, why it is the same

Built inside an Obsidian vault by an agent, for three kids who deserved better than a worksheet. The story of how they got made is on the blog.