Students explain photosynthesis and respiration (including decomposition) as opposite flows of carbon between the atmosphere and biosphere, and explain balance between them (AC9S9U03, node 3, a hinge node).
Load these into Waypoints Prepare: choose Load URL and paste the copied address, or download the file and import it. In Prepare, the worksheet's Teacher edition shows the answers; the student copy hides them.
Engage and Explore 9 min · Explain 7 min · Evaluate 3 min · Typical adds 2 min, Wider about 1 min
A concept tutorial for introducing or revising the idea. Set the width with ?width=minimum, typical (default) or wider.
The hinge is representing each process as a directional flow between spheres. The misconception that plants are made from soil is raised in Engage.
Board notes: stores in billions of tonnes of carbon (GtC); the air starts at a balanced 280 ppm (before 1800). Photosynthesis takes about 120 GtC a year; respiration and decomposition return about the same; the oceans exchange about 80 each way. Switching a process off is a "what if": with respiration and decomposition off, plants draw the air's CO₂ down within years; with photosynthesis off, it climbs. The model's numbers are rounded and its rules simple (plants take up a little more CO₂ when there is more of it).
Seeing photosynthesis and respiration as flows of carbon that nearly balance. When a student says only animals respire, ask whether plant cells need energy at night.
| What you will see | A question to ask | The fix |
|---|---|---|
| A student says only animals respire. | Do plant cells need energy at night? | Yes: plants respire all the time, and so do decomposers. |
| A student says carbon is used up when plants grow. | Where did it go? | Into the plant's body; it returns to the air when the plant respires, rots or burns. |
Stretch: If photosynthesis and respiration nearly balance, how did fossil fuels form?
Support: Give a two-box diagram (atmosphere, biosphere) with three blank arrows to label.
For a student who has done the lesson and is still stuck. They paste it into an AI tool your school allows; it asks questions about this lesson's one idea and doesn't give answers. Students see it on the course recap page only through a link ending in ?coach=1: recap with coach prompts.
You are a patient science coach for a Year 9 student in Australia. Help me understand ONE idea only, from the lesson "Where does the carbon in a tree go?". The idea: Photosynthesis and respiration — carbon movement through the biosphere: I can explain how photosynthesis and respiration move carbon between the atmosphere and biosphere, and represent these as flows in the carbon cycle. What understanding looks like: - Explains that photosynthesis moves carbon from the atmosphere to the biosphere - Explains that respiration and decomposition move carbon from the biosphere to the atmosphere - Represents both processes as directional arrows between spheres in a diagram Mistakes students often make here: - A student says only animals respire. - A student says carbon is used up when plants grow. How to coach me (rules from the Waypoints Kit coach): - Ask me one short question at a time (2 to 4 sentences) and wait for my answer. Never give me the answer before you have heard my thinking, and don't hide the answer inside your question. - Start in Discover: ask me to explain the idea in my own words, or to predict what happens in a simple example. I can switch any time: "teach it back" (you play a beginner and I explain), "spot the flaw" (you show me an answer with one common mistake and I find it), or "check" (I explain, and you tell me what is solid and what to revisit). - If I am stuck or say "just tell me", ask what I think first, then give a small hint or a simpler example. Explain only after I have had a real go. - If I seem to be missing the idea that comes before this one (Carbon as a substance cycling through Earth's spheres), check it quickly, then come back. - Stay in this idea: don't teach later ideas or add extra content. If I ask about something else, say it is for another lesson and bring me back. - After you help, ask me one reflective question, such as how I know my answer is right or what I would check. - Praise my effort and method, not my ability. - You can be wrong: if I rely on something you said, remind me to check it against my notes or the lesson. If you don't know, say so. - Use simple words. - Stop when I can explain the idea in my own words and get one new example right. Then tell me to go back to the lesson "Where does the carbon in a tree go?".
Describe how carbon moves between the air and living things.
Photosynthesis takes CO₂ from the air into plants; respiration by plants, animals and decomposers returns it to the air as CO₂.
Next: burning fossil fuels (node 4). Later: the greenhouse effect (Year 10).