Inventors Ladder · Free, age 10 to adult
Meet the people who tried, failed, and tried again until it worked
How did Archimedes test a king's crown? Why did Edison try thousands of filaments? How did two bicycle makers learn to fly? Each lesson tells one inventor's story: the problem they faced, how the idea came, what they tried, what failed, and what it led to, with short passages in their own words where the text is old enough to share. Pictures you can play with show the science, practice checks your answers, and the From Scratch course lets you build a battery, a motor, a telegraph and a radio yourself. No sign-up, nothing to pay.
From Scratch
Build it yourself, the way the inventors did: a lemon battery, an electromagnet, a simple motor, a hand generator, a telegraph, a crystal radio, and a printing press you can set type on.
The ladder
Each rung is a full course. Start where you are; topics from earlier rungs come back when you need them.
- High school
- Modern ExplainersGrade 8–12 · 4 topics You are here
- Middle school
- From ScratchGrade 4–9 · 8 topics You are here
- FlightGrade 6–10 · 2 topics You are here
- The Age of ElectricityGrade 6–10 · 7 topics You are here
- The Scientific RevolutionGrade 6–10 · 2 topics You are here
- Renaissance and the Printing PressGrade 5–9 · 2 topics You are here
- Ancient and Medieval InventorsGrade 5–9 · 3 topics You are here
How the Inventors Ladder works
- Find your rung. A short check, at most 30 questions, skips what you already know and finds your starting point.
- Learn from first principles. Each topic is one small idea. The lesson shows why it works, then walks through worked examples one step at a time.
- Master it before moving on. Three right answers, the last two in a row, pass a topic. If a topic gets hard, we point you to the skill underneath it.
- Review, spaced out. Passed topics come back after 1 day, then 3, 7, 16 days and longer, for two quick problems each. Harder topics that use an older one count as practice for it.
- Mix it up. Reviews and checkpoint quizzes mix problems from different topics, so you learn to tell which method a problem needs.
- Earn XP. About one point per minute of focused work. Set a daily goal and keep your streak going.
- One climb across subjects. Every ladder shares your XP, streak and reviews. When a topic needs a skill from another ladder, such as the algebra behind a formula, that skill comes first, labeled with its ladder.
Why these steps: the U.S. Institute of Education Sciences practice guide Organizing Instruction and Study to Improve Student Learning (Pashler and others, NCER 2007-2004) recommends spacing reviews out over time, alternating worked examples with problems students solve on their own, pairing pictures with words, and using quizzes to bring key content back. The Inventors Ladder is built around those ideas.
Try it in the Science Lab
Simulations to play with alongside the lessons.
- The ElementsAll 118 elements in an interactive periodic table: spin each atom in 3-D as shells or real …
- Magnetic Bottles for FusionTurn, slice and mirror-test two exact 3-D magnetic bottles for fusion from a new 2026 paper, …
- Newton’s Laws of MotionA six-chapter unit: Galileo’s ramps, F = ma with live graphs, skaters pushing apart, ramps …
- The Laws of ThermodynamicsA five-chapter unit: heat flowing between blocks, a piston on a P–V diagram, a gas run …
- Book CartSwing a chain of 2 to 25 books up from a rolling cart and balance it, or stand every book …
- Orbit LabFire Newton's cannon until the ball falls all the way around the world, put satellites in …
- Rocket BuilderBuild a rocket from engines, tanks and up to three stages, then fly it to space, to orbit or …
- Trebuchet WorkshopTune a counterweight trebuchet to hit a tower 100 to 300 meters away, follow the falling …
- Great Books LadderRead Archimedes, Galileo, Newton and Faraday in their own books
- The Chemical History of a CandleFaraday's famous lectures for young people
- Circuits in the Science LabBuild circuits on screen before you touch a battery
- Physics LadderLevers, light, electricity and magnetism, step by step
- TimelineWhere each inventor fits in history
- Every Science Lab simulation14 for this subject, and more
The other ladders
- Math LadderFrom counting in Pre-K to calculus, linear algebra and differential equations. 28 courses.
- Physics LadderHands-on science for ages 9 and 10, then motion, forces and energy, fluids, heat, electricity, light, atoms and the stars, up to college. 11 courses.
- Chemistry LadderAtoms, bonds, moles and reactions, from high school chemistry through a full year of general chemistry. 3 courses.
- Economics LadderHow people, firms and whole economies choose: microeconomics, macroeconomics and calculus-based micro. 3 courses.
- Earth & Space LadderRocks, plates and volcanoes, oceans, weather and climate, and Earth's place among the planets and stars. 3 courses.
- Logic LadderClear thinking, from arguments and fallacies to syllogisms, truth tables and formal proofs, grade 7 to college. 3 courses.
- Etiquette LadderManners as kindness made into habits: please and thank you, the table, conversation, notes and hard moments, age 4 to adult. 3 courses.
- Egyptology LadderAncient Egypt from the Nile and the pyramids to reading hieroglyphs: history, Middle Egyptian, religion and art, and archaeology, age 8 to college. 6 courses.
- Ancient Scripts LadderHow ancient scripts work and how they were read again, beginning with Linear A and Linear B of the Bronze Age Aegean, high school to college. 1 courses.
- Vocabulary LadderOne thousand advanced words, each with a picture and a memory hook, plus the Greek and Latin roots that unlock them, grade 6 to adult. 2 courses.
- Biology LadderLiving things from seeds and tadpoles to cells, genes, evolution and ecosystems, age 5 through AP Biology and college. 4 courses.
- American History & Civics LadderThe American story and how its government works, from the flag and the Pilgrims and stories from world history for ages 9 and 10 to AP U.S. History, civics and the citizenship test, and on to law school courses in constitutional law. 8 courses.
- Writing & Grammar LadderFrom a first sentence to the persuasive essay: grammar and diagramming, usage and punctuation, paragraphs and essays, sources and citations, and rhetoric, age 6 to college. 6 courses.
- Geography LadderMaps and directions for young explorers, then the fifty states, the countries and capitals of the world, and human geography up to AP, age 5 to adult. 4 courses.
- Art & Drawing LadderDrawing from first lines to perspective and faces, color and design, and art history from the cave painters to mid-century modern, age 5 to college. 5 courses.
- Memory LadderHow memory works and how to use it on purpose: spaced review, retrieval, chunking, pictures, mnemonics and the memory palace, then the Major System, PAO and the tools memory athletes use, age 8 to adult. 2 courses.
- Great Books LadderEvery work in the 60 volumes of Great Books of the Western World, one rung at a time, from Homer to the 20th century, with paths for young readers, teens and adults. 9 courses.
- Robotics LadderRobots from a cardboard arm at age 8 to circuits, Arduino and Raspberry Pi, arm kinematics, PID control, Kalman filters, path planning, ROS 2 and robot vision, with an honest six-month roadmap. 10 courses.
All the ladders share one progress: XP, your streak and your reviews.
Your progress is saved in this browser
No account needed. To move to another device, or to keep a backup, copy your save code and paste it in on the other device.
See your progress · The site's My Progress page backs up everything at once.