28 core topics
+ 31 prerequisite topics taught
as needed · approximately 15 hours of instruction
including spaced review
· premium unlock $24.99
An adaptive diagnostic (up to
40 questions) places the student on the course's knowledge
graph — topics already known are credited, and instruction begins exactly
at the learning frontier. Every topic is taught with a worked-example
lesson and auto-graded practice; a topic is mastered at
75%+ and then maintained through spaced reviews on an
expanding schedule. A cumulative quiz follows every 6
lessons. Prerequisite gaps below the course are detected and taught rather
than skipped, so completion certifies the whole tower, not just the top.
| Angle Relationships
[E] |
Vertical, complementary, and supplementary angle pairs. |
| Parallel Lines & Transversals
[E] |
Angle pairs formed when a transversal crosses parallel lines. |
| Triangle Angle Sum
[E] |
The three angles of a triangle always add to 180°. |
| The Pythagorean Theorem
[M] |
In a right triangle, a² + b² = c². |
| Distance & Midpoint
[M] |
Measuring segments in the coordinate plane. |
| Similar Triangles
[M] |
Same shape, different size: corresponding sides are proportional. |
| Perimeter & Area
[E] |
Measuring around and inside basic shapes. |
| Circles: Area & Circumference
[M] |
C = 2πr and A = πr². |
| Composite Areas
[H] |
Adding and subtracting simple shapes to measure a complicated one. |
| Volume: Prisms & Cylinders
[M] |
Volume = base area × height. |
| Volume: Cones, Pyramids & Spheres
[M] |
Pointed solids hold one third of the matching prism; spheres use 4/3 πr³. |
| Surface Area
[M] |
The total area of all the faces of a solid. |
| Special Right Triangles
[H] |
The 45-45-90 and 30-60-90 side ratios. |
| Arc Length & Sector Area
[H] |
A central angle takes the same fraction of the circumference and the area. |
| Modular Arithmetic
[M] |
Working with remainders directly. |
| Counting Divisors
[M] |
Divisor count from the prime factorization. |
| GCD & LCM Relationships
[M] |
The identity gcd(a,b) · lcm(a,b) = a · b. |
| Digit Problems
[M] |
Reasoning about the digits of a number. |
| Units Digit of Powers
[M] |
Combine last-digit cycles, then add. |
| Permutations
[M] |
Ordered arrangements. |
| Combinations
[M] |
Unordered selections: n choose k. |
| The Pigeonhole Principle
[M] |
Guaranteeing a repeat. |
| Complementary Counting
[M] |
Count the opposite, then subtract. |
| Counting & Probability
[H] |
Favorable outcomes over total outcomes. |
| Vieta's Formulas
[H] |
Relating roots to coefficients without solving. |
| Telescoping Sums
[H] |
A sum that collapses to its endpoints. |
| Sums, Parity & Invariants
[M] |
Elegant closed forms and even/odd reasoning. |
| Recursion & Sequences
[M] |
Each term built from earlier ones. |