Quizzes
Three quick questions after each lesson, so you know it stuck before you move on.
Free visual lessons · maths, physics, chemistry, coding, system design
See the idea move.
Each lesson builds one idea on screen, step by step: a one-minute short, a few-minute lesson, or a full walkthrough. For students up to grade 12, anyone learning to code, and anyone preparing for a system design interview.
19 lessons herefrom 1-minute shortsto 15-minute walkthroughsup to 60 minutes when a topic needs it
A few moments from the lessons, no sound.
Tap any lesson below to watch it with sound.
Lessons
Pick an idea. Watch it happen.
Tap a lesson to play it here, on a big screen or full screen. The pictures run the real thing: a real stack, a real search, real forces.
~1 min
Shorts
One idea, start to finish. Made for your phone.
3–6 min
Lessons
A whole topic, like simple harmonic motion or the sliding window.
10–15 min
Walkthroughs
A full LeetCode problem or exam question, every step shown.
Up to 60 min
Full length
A whole system design interview or textbook chapter in one video, with chapters to jump between.
Lessons
6 lessons · 3–5 min each · new on YouTubeA full topic in a few minutes. Walkthroughs of 10 to 15 minutes and full-length lessons of up to an hour are on the way.
Computer Science in 60 Seconds
6 lessonsData structures and algorithms, each ending with a few lines of Python.
Maths Proved with Physics
7 lessonsWeights, strings, water and light do the algebra. Ideas from Mark Levi's book The Mathematical Mechanic, explained in our own words.
Coming soon
Watch it, then make it stick.
Each lesson will come with a quick quiz, flash cards and a bot you can ask about any step. More lessons and subjects are on the way too.
Flash cards
The key facts from every lesson on cards you can flip: formulas, definitions, how fast each method is.
Doubt Bot
Stuck on a step? Ask Doubt Bot about the lesson you just watched and get a plain-words answer.
Competitive and entrance exams
JEE Main and Advanced, the SAT, and other exams in the US and around the world, solved one step at a time.
Real interview questions
A video explanation for each coding interview question, plus a code editor to write and run your own solution.
System design interviews
A whole interview, from requirements to deep dives, in one video.
More subjects
Added based on what you ask for. Tell us what you want next.
How it's made
Every frame is drawn, not filmed.
Our own animation engine draws each lesson from a script, so the picture always matches what the narrator says.
Step 1
One idea, one line at a time
The script is written like a teacher talking to one student: a question, the idea built in small moves, one worked example, a recap. It's written with AI help and checked by a person.
Step 2
Pictures that compute
The figures run the actual algorithm or the actual physics. The breadth-first search numbers come from a real search, and the doughnut's 395 cm³ is worked out, not typed in.
Step 3
Voice, sound, then a check
A narrator voice, music and sound effects go on, then an automatic check looks for words that overlap or run off the screen before a lesson is published.
For teachers, tutors, creators and developers
Make lessons like these from your own topic.
We're turning the engine behind these videos into a tool. You give it a topic, make it yours, check the script, and get a finished lesson. We're opening it to a small group first.
- From a 1-minute short to a 60-minute lesson with chapters
- Your voice, narration pace, teaching style and look
- Maths, physics, chemistry, code and system design for now, with more subjects as people ask for them
- You read and approve the script before anything is made
Join the engine waitlist
You're on the list ✓
We'll email you when the engine opens. Thanks for telling us what you'd make.
New lessonPreview
Topic
Why does ice float on water?
Voice
SlowerFaster
Style
Look
Format
Length
Try the settings. The engine opens to the waitlist first.