HS-LS1-5: Photosynthesis and Stored Chemical Energy
Also called NGSS HS-LS1-5 · Topic: Matter and Energy in Organisms and Ecosystems · Life Science
The Official Wording
Use a model to illustrate how photosynthesis transforms light energy into stored chemical energy.
Clarification statement: Emphasis is on illustrating inputs and outputs of matter and the transfer and transformation of energy in photosynthesis by plants and other photosynthesizing organisms. Examples of models could include diagrams, chemical equations, and conceptual models.
Assessment boundary: Assessment does not include specific biochemical steps.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What HS-LS1-5 Means in Plain English
Students use a model, such as a diagram or a balanced equation, to show how plants and algae capture light energy and store it in the bonds of sugar. They track matter too: carbon dioxide and water go in, and glucose and oxygen come out.
The model shows inputs, outputs and energy changes, not the separate light reactions or the Calvin cycle step by step. It builds on MS-LS1-6 and pairs with HS-LS1-7, where cells release that stored energy in cellular respiration.
HS-LS1-5 I Can Statements
- I can write the inputs and outputs of photosynthesis.
- I can explain how light energy ends up stored in sugar.
- I can use a balanced equation to show atoms are conserved.
HS-LS1-5 Worked Example
The floating leaf disk test, a classic lab where tiny spinach circles rise as they make oxygen.
Does the amount of light change how fast leaf disks photosynthesize?
Set It Up: Fresh spinach leaves, a hole punch, a plastic syringe, water with a pinch of baking soda and a drop of dish soap, clear cups and a desk lamp.
- Punch ten disks per cup and pull the air out of them in the syringe of baking soda water.Disks sink to the bottom
- Set one cup 10 cm from the lamp and another 40 cm away.Same disks and solution, different light
- Put a third cup in a dark cupboard as a control.Dark cup: disks stay sunk
- Count floating disks every minute in the two lit cups.Near cup: first disk rises at about 6 min
- Record the time when half the disks float in each cup.Near: about 10 min. Far: about 22 min
Disks under bright light floated about twice as fast, and disks kept in the dark never floated.
Why it works: Light energy drives the plant to build sugar from carbon dioxide and water, and the oxygen given off fills the air spaces in the leaf so the disks rise.
Common Mistakes with HS-LS1-5
Thinking plants get their mass from soil
“The plant's mass comes from the soil it grows in”
Try this: Most of a plant's dry mass comes from carbon dioxide taken in from the air. Soil supplies water and small amounts of minerals.
Saying light turns into matter
“Light becomes the sugar”
Try this: Light is energy, not matter. The atoms in sugar come from carbon dioxide and water, and light supplies the energy stored in its bonds.
Forgetting that plants respire
“Plants make oxygen, animals make carbon dioxide”
Try this: Plants also run cellular respiration day and night to use their sugar. In bright light, photosynthesis simply outpaces it, so oxygen is released overall.
Where HS-LS1-5 Fits
Practice HS-LS1-5
Quick Check
- What are the inputs and outputs of photosynthesis?
- Why did the leaf disks in the dark stay sunk?
- Does 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ conserve atoms?