Course library
What are you learning?
Choose a class and start with a free lesson. Every course keeps lessons, flashcards and practice together.
Subject 01
Mathematics
Numbers, shapes, structure and reasoning. 7 classes: Pre-Algebra, Algebra 1, Geometry, Algebra 2, Pre-Calculus, Calculus and Statistics & Probability. 292 free lessons in all, each chapter with flashcards and a practice test.
Pre-Algebra
Integers, fractions, percents and equations that get you ready for Algebra 1.
Algebra 1
Expressions, equations, functions, and linear relationships.
Geometry
Points, lines, planes, angles and the proofs that connect them.
Algebra 2
Functions in depth: polynomials, complex numbers, logarithms, conics, trigonometry and modeling.
Pre-Calculus
Functions, trigonometry, vectors and conics, with a first look at limits before calculus.
Subject 02
Science
Life and physical sciences. 7 classes: Biology, Physical Science, Chemistry, Physics, Earth & Space Science, Environmental Science and Astronomy. 255 free lessons in all, each chapter with flashcards and a practice test.
Biology
Cells, genetics, evolution and ecosystems: how living things work and change.
Physical Science
Matter, energy, motion, and forces.
Chemistry
Atoms, the periodic table, bonding, reactions and the mole, from measurement to energy.
Physics
Motion, forces, energy, waves, light, electricity and magnetism.
Earth & Space Science
Rocks, plate tectonics, water, weather and climate, out to the solar system and stars.
Subject 03
Social Studies
7 classes: Civics, U.S. History, World History, Economics, Psychology, European History and African & Asian History. 207 free lessons in all, each chapter with flashcards and a practice test.
Civics
How U.S. government works: the Constitution, rights, the three branches, elections and policy.
U.S. History
From Indigenous America and colonization to the Civil War, the world wars and today.
World History
Early civilizations to the contemporary world, with empires, trade, revolutions and war.
Economics
Choices, markets and prices, money and banking, and how whole economies grow.
Psychology
The brain, perception, learning, memory, development and mental health, studied as a science.
Subject 04
Life Skills
2 classes: Personal Finance and Business & Entrepreneurship. 45 free lessons in all, each chapter with flashcards and a practice test.
Subject 05
Arts
One class: Art History. 30 free lessons in all, each chapter with flashcards and a practice test.
Subject 06
Test Prep
4 classes: SAT Vocab 1, SAT Vocab 2, SAT Vocab 3 Double Meanings and SAT Math. 202 free lessons in all, each chapter with flashcards and a practice test.
SAT Vocab 1
The core words SAT reading questions use, like analyze, infer and evaluate, learned in context with flashcards and practice. Start here.
SAT Vocab 2
Harder SAT words for nuance and tone, like corroborate, ambivalent and mitigate, practiced in full-sentence questions.