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Learn Geometry

A free, interactive geometry course that starts with angles. Every problem comes with its own figure, the unknown angle becomes an equation on the board, and each step you take is checked as you make it.

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1,000+ codders enrolled

62 lessons54 challenges250 quiz questions

Syllabus

1 sections62 lessons54 challenges250 quiz questions
  1. Section 1

    Angles

    Start sectionStartExpandCollapse    Angles from the ground up: naming and measuring them, the pairs a straight line and a full turn create, vertical angles, parallel lines cut by a transversal, and the angle facts every triangle obeys.62 lessons54 challenges250 questions

    Meet the Angle

    6 lessons320

    Straight Lines and Supplements

    5 lessons520

    Right Angles and Complements

    5 lessons420

    Vertical Angles

    5 lessons520

    Around a Point

    5 lessons520

    The Angle Bisector

    4 lessons315

    Crossing Parallel Lines

    6 lessons525

    Transversal Problems

    5 lessons520

    Triangle Angle Sum

    5 lessons520

    Isosceles Triangles

    6 lessons425

    The Exterior Angle

    5 lessons520

    Final Challenges

    5 lessons525
What you get
Everything you'll use to learn math

Learn by Solving

Work every problem yourself on an interactive board. Each step is a move you choose, every line is checked, and graphs are drawn by hand.

Math board
Step by step
2x + 3 = 7Subtract 3 from both sides2x = 4Divide both sides by 2x = 2

Solving is a game of legal moves. You pick the move; every line follows from the one before it.

Build Your Math Streak

Stay consistent and watch your progress grow! Track your daily math habit, protect your streak with freeze days, and earn rewards for showing up every day.

12 days streak

Return tomorrow to keep your streak!

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January 2026

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Double or Nothing

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You're Not Alone in This

Compete on global leaderboards, invite friends to earn rewards, and celebrate each other's wins. Math is better with friends!

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Every way to learn

Read, listen, test yourself, ask the AI about your own steps, or look up anything you've already covered. Every lesson meets you where you are.

What an Equation Is
Audio

An equation is a claim: the two sides name the same number. The equals sign asserts sameness, it gives no orders.

A solution is a value of the unknown that makes the claim true. Substitute it and both sides agree.

Solving means changing the form without changing the claim - the same move applied to both sides keeps the balance.

1xSarah

Prove Your Skills

Earn a certificate when you complete a section. Add it to your LinkedIn profile to show how far your math has come.

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This certifies thatJohn Doehas successfully completed
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DateJan 2026
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Why learn geometry with Coddy

  • Every problem has a figure. The angles, lines and triangles are drawn for you, so you reason about what you see instead of what a sentence describes.
  • An unknown angle is an equation. When two angles make a straight line, the board holds x + 80 = 180, and you solve it with the same legal moves as any equation.
  • Every step is checked as you make it. The board offers only moves that keep the statement true, and a coach comments on your direction.
  • From the first angle to the triangle. Naming and measuring, pairs on a line and around a point, vertical angles, parallel lines cut by a transversal, and the angle sum of a triangle.

Frequently asked questions about learning geometry

What does the geometry course start with?

With a single angle: how it is named, how it is measured in degrees, and what acute, right, obtuse and straight mean. The first lessons build the vocabulary every later fact is written in.

Do I need algebra before geometry?

Only the simplest kind. Angle problems on the board turn into equations such as x + 80 = 180, and solving one takes a move or two. The algebra course teaches those moves from zero if you want them first.

How is a geometry problem solved on the board?

The figure shows the situation, the board holds the equation the figure implies, and you solve it move by move. Each move is checked as you make it, hints point at the next one, and the final line is the answer.

Which angle facts does the course cover?

Complementary and supplementary pairs, angles around a point, vertical angles, angle bisectors, the corresponding, alternate and co-interior angles of parallel lines cut by a transversal, and the interior and exterior angle facts of a triangle.

Is the geometry course free?

Yes. Every lesson, figure and check is free. A Pro plan removes the daily limit and adds unlimited help from the AI tutor, but the course itself is not behind a paywall.

Will more geometry sections be added?

Yes. The course opens with angles, the foundation every other topic rests on. Further sections are being written and will appear in the same course as they are published.
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Learn Geometry with Coddy

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