Mathematics
DSE Compulsory — live
Hong Kong secondary mathematics: three curriculum strands, starting with quadratic equations.
{% extends "base.html" %}
{% import "macros/social-icons.html" as social %}
{% block title %}{{ section.title }}{% endblock title %}
{% block meta_description %}
{% endblock meta_description %}
{% block content %}
High-quality learning materials for elementary school through university — on the web, at no cost.
Open textbooks. Free to read. Open to improve.
Catalog
DSE Compulsory — live
Hong Kong secondary mathematics: three curriculum strands, starting with quadratic equations.
Coming soon
Physics, chemistry, biology, and earth science from introductory to advanced levels.
Coming soon
History, literature, philosophy, and languages — readable, citable, and free to share.
Coming soon
Programming, computer science fundamentals, and practical skills for students and teachers.
Subject pages and full catalogs are on the roadmap. Contribute a book on GitHub.
Featured
DSE Compulsory Part
Number & Algebra, Measures Shape & Space, and Data Handling — with an interactive quadratic explorer.
Open source
Every book is a repository you can fork, translate, or adapt for your classroom.
Want to list a book? Open a pull request or start a discussion on GitHub.