New lessonDNA Replication

Biology you can take apart.

Interactive lessons, virtual labs, and simulations for AP and intro college biology. Run the experiment, break the pathway, build the cell — and see why it works.

Start learning Try the leaf disk lab
  • Aligned to the AP Biology CED
  • 9 hands-on lessons
  • Free, no sign-up
  • Works on your phone
Mitochondria~36 ATP per glucose
Not another slideshow

Every lesson is something you do.

Some lessons are labs. Some are simulations you can break. Some you build with your own hands. The ideas stick because you tested them.

Virtual lab

Photosynthesis

Run the leaf disk assay. Change light, CO₂, and temperature, then graph what happens.

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Simulator

Cellular Respiration

Cut off oxygen or add cyanide and watch the whole pipeline jam.

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Builder

Meiosis

Line up chromosomes, cross them over, and collect all 16 possible gametes.

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Step-through

DNA Replication

Open a replication fork and predict each enzyme's next move.

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How a lesson works

Explore. Predict. Experiment.

Built around how learning actually sticks: hands on the model, a guess before the answer, and a chance to test your idea.

  1. 1

    Explore

    Drag, tap, and scrub through a process until you can see how the pieces fit.

  2. 2

    Predict

    Commit to an answer before the reveal — the fastest way to find what you don't know yet.

  3. 3

    Experiment

    Change the conditions, run trials, and compare results like a real lab.

Topics

Pick where your class is.

All topics →
7 lessons

Cell Biology

Explore mitosis, organelles, and membrane transport

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2 lessons

Genetics

DNA replication, transcription, translation, and inheritance

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Coming soon

Ecosystems

Food webs, energy flow, and nutrient cycles

See what's coming

Start with one lesson.

Free, no sign-up, and it works on the phone in your pocket.

Browse lessons Try the gamete builder