Grade 7 science
The light a leaf and a panel both catch
A leaf and a solar cell have the same first job: absorb energy that arrives as light. They keep that energy in different forms. The bridge article is Infrared, which is a kind of light, so the route forces the class to talk about light itself.
- Course
- Grade 7 science, after photosynthesis is already underway
- Grade
- Grade 7. The life-science teacher owns this day. A physical-science colleague can visit for the spectrum line.
- Length
- 45 minutes. The race is 10.
- When
- OpenSciEd Unit 7.4, Matter Cycling & Photosynthesis, after students can say that light energy enters the chloroplast. That is mid-unit or later, around the lesson where the chloroplast model takes in light. It is a poor opening day.
Host this class opens a private 10-minute lobby, Photosynthesis to Solar cell, fewest clicks. Students see the start and the target. The answer key shows the chain, so keep it on your screen.
Do not project this page
It contains the route. Put the lobby PIN on the board. Leave this lesson on your own laptop, or print it and hold it.
One device per student, or one per pair. Phones work. Students can join as guests. No accounts.
These articles do not already link. The shortest route is 2 clicks.
Routes students can take
Photosynthesis → Infrared → Solar cell. A longer wander still counts if they reach the target. These are the short ones to expect.
Individual routes
1 shortest route. Hover a route to highlight it on the map.
- 12 clicks
PhotosynthesisPhotosynthesis is a system of biological processes by which photopigment-bearing autotrophic organisms, such as most plants, algae and cyanobacteria, convert light energy—typically from sunlight—into the chemical energy necessary to fuel th…
InfraredInfrared radiation is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves.
Solar cellA solar cell, also known as a photovoltaic cell (PV cell), is an electronic device that converts the energy of light directly into electricity by using the photovoltaic effect.
Who it is for
The grade 7 science teacher who has just established that plants need light to make food, and who wants that fact to meet the solar panel students already know from the roof or the parking lot.
OpenSciEd 7.4 builds MS-LS1-6, MS-LS2-3, and MS-PS1-3. Students model carbon, hydrogen, and oxygen moving, and they track sunlight becoming energy living things can use. Run this on a day after that light-in step exists. It does not replace the chloroplast lessons.
The measured chain is two clicks: Photosynthesis, Infrared, Solar cell. Infrared is the teaching point, and it is also the place students will overclaim. Plants mostly use visible light, red and blue, and reflect green. They are weak users of infrared. Many solar cells use visible light and some near-infrared. The shared fact is that both devices absorb light energy. Infrared is on the path because it is a page about light, not because a leaf is a solar panel.
Correct the analogy in the debrief or the lesson teaches the wrong science. A leaf stores energy in sugar. A solar cell makes an electric current. Same arrival, different storage.
Standards
- NGSS MS-LS1-6Construct a scientific explanation based on evidence for the role of photosynthesis in the cycling of matter and flow of energy into and out of organisms. This lesson is the energy-in half. The carbon-atom tracing stays in the rest of Unit 7.4.
- NGSS MS-PS4-2Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials. The infrared stop is how the class meets light as a spectrum that materials can absorb.
Before they walk in
They already need to know
- Students can say that a plant takes in light energy and, with water and carbon dioxide, makes sugar and releases oxygen.
- They do not need the electromagnetic spectrum yet. You will draw the small piece they need.
You do this
- Read the correction once: a leaf is a sugar-maker that absorbs light. A solar cell is a current-maker that absorbs light. Infrared names a band of light. It connects the articles because both stories are about light.
- Host from this page. Private lobby, Photosynthesis to Solar cell, 10 minutes, fewest clicks.
- On the board, only this: “A leaf. A panel on a roof. What is each one waiting for?”
The period
One arrival
Pairs answer the board question. You want “light” or “sunlight,” not “water” and not “electricity.” Electricity is what the panel produces. Water is an input to the leaf, not the thing the panel is waiting for. If someone says electricity, ask “waiting for, or giving off?”
Open the room
PIN and QR. Start page Photosynthesis, target Solar cell. Blue links only. Ten minutes. Fewest clicks. Tell them the path article is for you, after class, because it shows the chain.
The race
If a student is inside Chloroplast, Chlorophyll, or Glucose, ask “What arrived from outside the leaf?” That question points at light without naming Infrared. If they are in Solar power or Photovoltaics, they are close. Let them click.
The spectrum line
Reveal the chain: Photosynthesis, Infrared, Solar cell. Draw one line and label five bands in order: radio, infrared, visible, ultraviolet, X-ray. Under visible, write ROYGBIV small. Mark “a leaf mostly uses red and blue visible light, and reflects green.” Mark “a solar cell uses visible light and some near-infrared.” Ask why a page about invisible light was the door between a plant and a panel. The answer you are listening for: both are trying to catch light, so the article that names a kind of light connects them.
The claim they write
They copy and finish this, in their own words if they can: “A leaf and a solar cell both absorb light energy. A leaf stores it in sugar. A solar cell turns it into electric current. Infrared is one kind of light. It links the articles because the shared idea is light, even though a leaf mostly uses visible light.” Walk once and fix any sentence that says the leaf runs on infrared.
One check
Ask aloud: “Why is the bridge not Chlorophyll?” Take one answer, then give yours from the prompt list. That question tells you whether they found the shared idea or only the plant’s tool.
Answers you will need
Why is the bridge not Chlorophyll?
Chlorophyll is how the leaf catches light. It does not lead to the panel. The shared idea is light itself, so the article that names a kind of light is the door.
Do plants and solar panels both run on infrared?
No. Say that. A leaf mainly absorbs visible red and blue and reflects green, which is why it looks green. Infrared is a neighboring band. Some solar cells use part of the near-infrared as well as visible light. The click is still the right lesson: you cannot get from the leaf to the panel without passing through a page about light.
Is a leaf a solar panel?
They do the same first step and then different work. Both absorb light energy. The leaf builds sugar. The cell drives a current. Students who say “a leaf is a solar panel” have the arrival right and the storage wrong.
Exit
Why does Infrared sit between Photosynthesis and Solar cell? Write two sentences. One sentence must say what each device does with the energy after it absorbs the light.
A finished answer has
- Light, or energy from light, is the connection.
- Sugar and electric current are named as two different results.
Steer these
- “Plants are solar panels.” Ask what each one makes.
- “Infrared is the light plants prefer.” Point at the green leaf and ask which light bounced off.
If the period is short
Keep the race and the spectrum line. Skip the written claim and do the chlorophyll question aloud.
If the network fails
Ask them to predict the middle article before you say it. Draw the spectrum line, teach the correction about visible light, and have them write the two-sentence exit. Tell them the measured chain is Photosynthesis, Infrared, Solar cell.