Biology · Lesson Worlds

Photosynthesis: interactive science lab

Change light or carbon dioxide and prove that a leaf builds sugar from both.

Free · No account required · Runs in your browser

What will you learn?

A leaf needs light and CO₂ to make sugar. Dim the sun or starve the air and sugar slows.

How does the lab work?

Observe the simulation, make a prediction, change a variable, run the experiment, and explain the result. Finish with a challenge that tests your understanding.

You can change: Light, CO₂. Compare what happens and connect the result to the scientific explanation.

Try a comparison in Photosynthesis

Start with the lab’s initial settings. Choose one control below, predict the result, and change that control while keeping the others fixed. Record the setting and what you observe before making a second change.

Light: the lab starts at 50; its available range is 10–100.
CO₂: the lab starts at 1; its available range is 0.2–2.

For a named starting condition, try Dim, Room, Sun. A preset can change several settings: check the controls before treating two presets as a one-variable comparison.

Questions to discuss during the activity

Watch what happens. Sugar builds slowly. Watch a leaf in ordinary light.
Name the cause. Photosynthesis locks light energy into sugar. No light, no work. No CO₂, no carbon to lock. Both knobs matter. Light is energy. CO₂ is stuff.
Change something. Raise light and sugar should climb. Change light, then shine.
Guess before you run. If we raise light to 90, sugar will… Guess what will happen, then run to check.

After your comparison, explain how the observations connect to this idea: A leaf needs light and CO₂ to make sugar. Dim the sun or starve the air and sugar slows. Name one condition you held fixed and one feature of the real world this model simplifies. A completed run is a starting point for discussion, rather than proof of mastery.

Who is it for?

Curious learners exploring biology. A parent or teacher can help younger learners read the instructions and discuss the results. Choose by topic and prior knowledge rather than a fixed grade level.

Is this lab free?

Yes. This interactive lab is free without signing in or a paid membership.

No app download is needed; interactive play requires JavaScript and a modern browser.

Use this activity with a learner

Families and educators · choose by prior knowledge

Learning goal: A leaf needs light and CO₂ to make sugar. Dim the sun or starve the air and sugar slows.

Before you begin: Read the controls for Light, CO₂. Make one prediction before changing a setting.

Check understanding: Ask for one observation, the evidence that supports it, and a question to investigate next.

A simulation simplifies the real world. Explain which conditions stayed fixed; a successful run alone does not demonstrate mastery.

Investigate conditions for photosynthesis: prediction, evidence, and follow-up

Share Photosynthesis with your family or class. No account is needed to open the free resource.

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