Start where you are. Climb as far as anyone knows.
Free lessons, films and simulations in science, starting with biology. Ages 5 to graduate school. No account, no ads.
One idea, six levels.
Here is photosynthesis, from a small child’s version to a question researchers are still working on. Every lesson explains its idea at more than one level, so you can step down when you need to and up when you’re ready.
- A small childPlants need sun and water to grow.
- Elementary schoolPlants make their own food from sunlight.
- Middle schoolLeaves use light to turn carbon dioxide and water into sugar, and give off oxygen.
- High schoolIn chloroplasts, photosynthesis stores light energy as chemical energy in glucose.
- CollegeThe light reactions make ATP and NADPH, and the Calvin cycle uses them to turn carbon dioxide into sugar.
- A research labWhy does Rubisco so often grab oxygen by mistake?
Every level
Every lesson explains its idea at more than one level. Most run from a child’s version up to a graduate student’s.
Films and simulations
Nearly every lesson has a short film, and most have a simulation you can change.
Answers explained
Every practice question shows the answer and why.
Where are you starting?
Pick the line closest to you. Anyone can start on any rung. If a lesson moves too fast, every one has a simpler version of its idea.
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Ages 5–10, with a grown-up
You’re a parent or teacher with a young child. You run the activity together, away from the screen.
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Grade 7
You’re about 12, or you want biology from its first page.
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High school
You’re in high school, or you want the full high school course.
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Starting college
You’re starting college biology, or coming back to it after years away.
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College: the core
You know the basics and want what a biology degree covers.
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College: going further
You have the core and want one subject in depth.
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Graduate school and beyond
You want to read the current research and see the open questions.
Under five, or ready for chemistry, physics or math? Those rungs aren’t built yet. See what’s coming → See every course in full →
What do you want to do?
Each goal puts the free courses in an order that suits it. Your choice is saved on this device only, and you can change it any time.
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Get ready for the MCAT
The biology and biochemistry the exam leans on, with original MCAT-style questions and a review queue.
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Keep up with a class I’m taking
Grades 7–12, or a college biology class. Find your course and work through it in order.
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Teach with it
Free for your classes. Make a class with one link, set the level of help, and see the standards map.
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Learn for the love of it
No exam and no set order. Start with whatever you’ve wondered about.
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Reach the edge of research
Climb to the courses that end at the open questions, with the papers behind them.
Things to try
- Metabolism Arcade Six games from the Biochemistry course: wire the cell, fix a broken enzyme, and drill for the MCAT.
- MCAT practice Passages with data, a diagnostic and topic practice.
- The methods library How scientists find things out.
- The Fun Stuff Trading cards, memes, songs and a podcast, made by students in my biochemistry course (BIOL 3030).
Work in progress, built in public.
I put this up rough on purpose, and I fix it in the open. Lessons still being checked carry an Under review tag. Chemistry, physics, math and anything for under-fives aren’t built yet. If you find an error, tell me and I’ll fix it.
Report an error → How it’s made and checked →
Chris Deppmann