Where does the sunlight go?

Classroom resources

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.

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Students will be able to

• I can identify the sun as Earth's main energy source.
• I can distinguish absorbed from reflected sunlight with examples.
• I can explain why melting ice increases the energy absorbed.

Timing

Engage and Explore 6 min · Explain 6 min · Evaluate 3 min · Typical adds 1 min, Wider about 1 min

Before class

A concept tutorial for introducing or revising the idea. Set the width with ?width=minimum, typical (default) or wider.

The hinge is the absorbed–reflected split: without it students can't explain why surface changes alter the energy balance (node 2), or why the greenhouse effect is about outgoing, not incoming, energy (node 3).

Board notes: surface albedos are typical values (ocean 6%, forest 15%, city 12%, grassland 25%, desert 35%, ice and snow 80%). The absorbed figure uses Earth's average incoming sunlight (340 W/m²) for the surfaces shown; the whole planet's 30% includes clouds, which the row doesn't.

Running the lesson

1. Engage: count how many chose 'all of it warms the Earth'.
2. Explore: ask which button changed the reflected percentage most.
3. Explain: the melting ice question is the checkpoint.

The hard part (on purpose)

Linking a surface's albedo to how much energy it absorbs. When a student guesses from shininess, ask what percentage the board gives for that surface.

When students get stuck

Answers to the checks

1. Engage: does all sunlight warm the Earth?: Sunlight reaches the Earth. What happens to it?
   Some is reflected and the rest is absorbed. On average Earth reflects about 30%, mostly from clouds, ice and bright surfaces. Dark surfaces like oceans absorb most of what hits them.
2. Explore: change the surfaces: Change the surfaces until you have seen the percentage reflected change by at least 30 points.
   
3. Reflect or absorb: Reflects most sunlight, or absorbs most?
   Fresh snow → Reflects most; Open ocean → Absorbs most; Sea ice → Reflects most; Dark forest → Absorbs most; Thick white cloud → Reflects most
4. Melting ice: Arctic sea ice melts and is replaced by open ocean. What happens to the energy absorbed there?
   It increases, which warms the area and melts more ice
5. Light or dark: Why does fresh snow reflect most of the sunlight that hits it, while the open ocean absorbs most?
   Light-coloured surfaces reflect most of the light that hits them; dark surfaces absorb most of it and warm up
6. Elaborate: the angle of the sun: The same sunlight hits the equator nearly straight on, but the poles at a low angle. Why do the poles get less energy per square metre?
   The same beam is spread over a bigger area, and more is reflected at low angles
7. Elaborate: land use: A city replaces grassland with dark roads and roofs. What happens to the local energy budget?
   More sunlight is absorbed, so the city warms: an urban heat island
   Light-coloured roofs and more trees are used to cool cities.

Stretch and support

Stretch: Melting ice absorbs more, which warms, which melts more ice. What kind of feedback is that?

Support: Give a table of surfaces to rank by percentage reflected.

Coach prompt (optional)

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 10 student in Australia. Help me understand ONE idea only, from the lesson "Where does the sunlight go?".

The idea: Solar radiation and Earth's energy input: I can describe how solar radiation reaches Earth and identify the factors that determine how much energy is absorbed versus reflected by the surface and atmosphere.

What understanding looks like:
- Identifies the sun as the primary energy input to Earth's climate system
- Distinguishes absorbed from reflected solar radiation with at least one surface example
- Explains why different surfaces absorb or reflect different proportions of solar radiation

Mistakes students often make here:
- A student says the ocean reflects a lot because it's shiny.

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.
- 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 sunlight go?".

Exit ticket

Why does replacing sea ice with open ocean warm the area?

Ice reflects most sunlight (about 80%); dark ocean absorbs most (reflects about 6%), so more energy is absorbed.

What each step is for

• Engage: does all sunlight warm the Earth?: Students who treat sunlight as uniformly heating Earth miss reflection; the board splits incoming light into reflected and absorbed for each surface.
• Explore: change the surfaces: Changing surfaces and watching the reflected and absorbed amounts shift makes albedo a measurable property.
• Explain: absorbed and reflected: Ranking surfaces and predicting the effect of change is the base the energy balance builds on.
• Elaborate: the angle of the sun: Angle of incidence explains why the poles get less energy, linking to Year 7 seasons.
• Elaborate: land use: Predicting the local energy effect of land-use change applies albedo to human decisions.

Where it leads

Next: energy balance between the spheres (node 2), then the greenhouse effect (node 3).