9 units
Algebra I
Foundations
The language the rest of math is written in. Start with equations, finish able to model a real situation with a function.
- Linear equations & inequalities
- Systems of equations
- Functions, slope & graphing
Free, self-paced math · Grades 8–12
Master the math that class moves past too quickly.
49 units across 6 courses, written one idea at a time. Every lesson ends with a problem set and a full worked solution — so you always know why an answer is right, not just that it is.
- 6 courses
- 49 units
- Worked solutions
- No account needed
This week's focus
Quadratics & the discriminant
- 01Standard form: ax² + bx + c = 0
- 02Discriminant: b² − 4ac decides the roots
- 03Positive → 2 real · Zero → 1 · Negative → complex
Unit 3 of Algebra II · 11 problems, 3 worked examples
The curriculum
Six courses, in order or out of it
No placement quiz and no lockstep. Jump into whichever course is on your desk this week.
8 units
Geometry
Foundations
Reasoning you can defend. Every theorem is built from postulates you already understand, one justified step at a time.
- Proof & logical reasoning
- Congruence & similarity
- Circles, area & volume
10 units
Algebra II
Intermediate
Where algebra gets interesting: curves instead of lines, and a number system that finally closes under every operation.
- Quadratics & complex numbers
- Polynomials & factoring
- Logarithms & exponentials
9 units
Pre-Calculus
Advanced
The bridge course. Trigonometry, vectors and series, taught so that limits later feel like a natural next sentence.
- Trig identities & the unit circle
- Vectors & polar coordinates
- Sequences & series
7 units
Statistics
Applied
How to make a claim you can defend with data — and how to spot one that can't be. Built around real datasets.
- Describing & displaying data
- Probability & distributions
- Sampling & regression
6 units
Calculus Readiness
Advanced
A short, focused run at the ideas underneath a first calculus course, without the grading curve.
- Limits & continuity
- Derivative intuition
- Rates, optimization & graphs
Practice
Four problems, right now
A sample from across the courses. No sign-in, no timer — work each one on paper first, then check the reasoning against ours.
Every solution shows the reasoning, not only the answer
01
Solve for x: 3x − 7 = 20
02
Factor completely: x² − 5x + 6
03
A right triangle has legs of 6 and 8. Find the hypotenuse.
04
Simplify: (2x³)(4x⁻¹)
The method
Short lessons, honest problems, real review
01
Read one short lesson
Every unit opens with a single idea, one fully worked example, and only the notation you'll actually be asked to use.
02
Work a short problem set
Five to ten problems per lesson, ordered from warm-up to challenge, each with full solutions instead of just an answer key.
03
Review what slipped
Anything you miss moves to a review list, so the topic comes back around before it has a chance to disappear.
Start with the course on your desk
Every unit is open, and nothing is behind a paywall.