Euclid's Workshop
A Study Companion
The foundation of mathematical thinking, made approachable.
What is Euclid's Elements?
Written around 300 BCE, Euclid's Elements is one of the most influential works in the history of mathematics. For over two thousand years, it was the standard textbook for teaching geometry and logical reasoning.
Book I begins with just 23 definitions, 5 postulates, and 5 common notions, then builds 48 propositions, each proven using only what came before. It shows how complex knowledge grows from simple foundations.
This study companion pairs Euclid's original text with plain-language explanations, interactive diagrams, and historical context to make this ancient wisdom accessible to modern learners.
How to Use This Guide
Learn how the toolkit builds as you progress, and get the most from your study.
The Foundations
23 Definitions, 5 Postulates, and 5 Common Notions: the building blocks of everything that follows.
The Propositions
48 proofs that build from simple constructions to the Pythagorean theorem, step by step.
About This Project
Learn about our approach to making Euclid accessible and the sources that inspired this companion.
Teaching Curriculum
Lesson plans, worksheets, and answer keys: everything you need to teach Euclid's geometry.
The interactive course is free, forever. If you're teaching it, the curriculum pack saves you the prep.
Foundations
$9
Full curriculum for Propositions 1–26: constructions through triangle congruence.
Buy FoundationsAdvanced
$12
The second half, Propositions 27–48: parallels → angle sum → the Pythagorean theorem.
Buy Advanced