Overview

Rechenkiste (“math box”) is a maths practice app for primary school children, grades 1 to 5. A child picks a grade and a number of tasks, answers one task after the other and gets feedback and a hint after every answer. At the end a result page lists every task with the given and the correct answer.

The app runs at rechenkiste.casoon.dev, in German, English and Ukrainian.

It is also a working demo of two things:

• the AHA stack: Astro renders on the server, htmx swaps HTML fragments, Alpine.js handles small pieces of local state such as the number pad;
• @casoon/fragment-renderer, which renders Astro components to HTML strings inside API routes, so htmx gets real components instead of hand-built template strings.

What a child can practise

105 task types across six categories: arithmetic, word problems, geometry, number sense, measurement, and data. They cover mental and written arithmetic with the four operations (division with remainder included), negative numbers, number sequences, neighbours and comparisons, fractions, decimals and percentages, counting shapes, perimeter, area and volume, coordinates, symmetry, bar charts, reading clocks and time spans, money, and units of length, weight, volume and area.

Answers come in as free text, via an on-screen number pad, as multiple choice or by drag and drop. Geometry, fraction and clock tasks draw their figure as SVG.

This documentation

• Getting started – running the app locally and deploying it to Cloudflare Workers.
• Architecture – the request flow through Astro, htmx and the fragment renderer, the task system and the session.
• Reference – API routes and the task catalogue.