Unit 5 · Cells & Living Systems · Week 5 · Performance task

Can you model how a living thing takes in, transforms, and uses matter and energy to stay alive?

The windowsill plant started as a tiny seed. Now it's a leafy stem with roots — made almost entirely of matter that was not in the seed. Where did all that matter come from? And how does the plant (or you) keep every single cell powered up, every minute, without running out? Can you draw a model that shows the whole story — from sunlight and CO₂ to a working, living body?

SEP: Developing & Using Models · Constructing Explanations DCI: LS1.C Organization for Matter & Energy Flow in Organisms — photosynthesis + cellular respiration; LS1.A Structure & Function; LS1.B Growth & Development CCC: Energy & Matter — matter is conserved; energy is transformed, not created

NGSS MS-LS1-6 · MS-LS1-1 · MS-LS1-2 · MS-LS1-3 ~60 minutes (performance task) Learner code: —

Make this lesson work for you:

Start here

How we work today (our expectations)

This is YOUR thinking — bring in everything you built this unit
A model doesn't have to be perfect — it has to show your reasoning
Matter and energy don't appear from nowhere — trace where they go
Open any support panel — they belong to you, any time

30-second check-in self-awareness + self-management

Unit 5 ends today. Before anything else, think back to Week 1 — you were wondering how a seed can become a plant when the pot loses almost no soil. You now have four weeks of ideas about that. Take one slow breath. Name one idea from this unit that feels solid to you right now. That idea is your anchor for the next 60 minutes.

Do-Now Retrieve the whole unit

Four questions — one from each week. No looking back. Pulling these ideas from memory now makes the modeling task stronger.

Week 1 spiral A cell is the basic unit of life. Name two things every cell must do to be considered alive. Then name one structure inside a plant cell that you would NOT find in an animal cell — and explain what it does.
Week 2 spiral A willow tree grows from a 20-gram seed to weigh 500 kilograms. Most scientists once thought the extra mass came from soil. We now know it comes from the air and water. Describe the process that explains this — and name the reactants (what goes in) and the products (what comes out).
Week 3 spiral A plant full of glucose is moved to a dark closet. It slowly withers. Explain why, using the word cellular respiration. What does the cell do with glucose, and what happens to the stored energy?
Week 4 spiral Your body has about 37 trillion cells. Each one needs oxygen and glucose every minute. Describe how two different body systems work together to deliver those supplies to a muscle cell deep inside your leg.

The anchor phenomenon

The windowsill plant from Unit 5 — now showing the full matter-and-energy story. Sunlight energy is captured and stored in glucose (photosynthesis). That glucose is broken down to release the stored energy for life (respiration). The atoms of carbon, hydrogen, and oxygen cycle through — they are never created or destroyed.

Look carefully at the diagram. A seed weighing less than a gram became the plant on the windowsill. The seed's mass came almost entirely from carbon dioxide gas in the air and water from the soil — not from the soil itself. Sunlight provided the energy to attach those carbon atoms together into glucose molecules, storing the sun's energy in chemical bonds. Every night, and every time any cell does work, some of that stored glucose is broken apart by cellular respiration — releasing the stored energy for growth, movement, and repair, and releasing the carbon atoms back into the air as CO₂. The atoms that make up the plant's leaves, stem, and roots were once floating invisibly in the air outside the window. How is it possible that a plant can be built almost entirely out of thin air — and where does the energy that holds it all together come from?

Notice & Wonder. Write one thing you notice in the diagram that connects to something from an earlier week in this unit. Then write the one question you most want answered by the end of today.

Tie it together One connected model of matter and energy

Weeks 1–4 each gave you one piece of the story. Here they connect into a single, powerful model of life.

Look at the unit arc: Week 1 — the cell is the basic unit of life; all living things are made of cells, and cells carry out the basic functions of life (taking in matter, releasing energy, growing, reproducing, responding). Week 2 — plants use photosynthesis (CO₂ + H₂O + light energy → glucose + O₂) to capture the sun's energy and store it in the chemical bonds of glucose; almost all the mass of a plant comes from CO₂ in the air — not from soil. Week 3 — every living cell — plant or animal — uses cellular respiration (glucose + O₂ → CO₂ + H₂O + usable energy) to release the stored energy in glucose so the cell can do work; no cell can function without this continuous energy release. Week 4 — in a multicellular organism, the delivery of matter (glucose, oxygen) and the removal of waste (CO₂, water) are handled by coordinated organ systems — the circulatory system moves materials, the respiratory system exchanges gases, the digestive system breaks down food — all so that every individual cell gets what it needs to run cellular respiration and do its job. The unifying insight beneath all four weeks: a living thing stays alive by continuously taking in matter and energy from its environment, transforming them through chemical reactions inside cells, and using the released energy to maintain its structure — while conserving every atom, sending none into or out of existence. This is the year's Energy & Matter throughline arriving at its payoff: the conservation of matter explains why a tree is made of air, and the conservation of energy explains why you must keep eating.

Worked example — tracing matter and energy through the windowsill plant (read before you model)

Step 1 — Where does the plant's matter come from? Jan van Helmont grew a willow tree for five years, carefully weighing the soil before and after. The tree gained more than 75 kg; the soil lost less than 60 grams. He concluded the mass came from water — but we now know it comes mostly from CO₂ in the air. During photosynthesis, a carbon atom from a CO₂ molecule in the air passes through a stomata on the leaf, enters a chloroplast, and is bonded into a glucose molecule (C₆H₁₂O₆). That carbon atom is now part of the plant's body. No matter was created — a carbon atom that was once in the atmosphere is now in a leaf cell's glucose. This is conservation of matter.

Step 2 — Where does the energy come from? The energy in the glucose bonds came from sunlight — a photon of light was absorbed by chlorophyll, and its energy was used to drive the reaction that attached carbon atoms together. The plant did not create energy — it captured energy from the sun and stored it in a chemical form. This is conservation of energy: energy changed form (light → chemical), but none was created or destroyed.

Step 3 — How does the stored energy get used? That same glucose molecule — packed with stored energy — travels to a cell that needs energy (a root cell, a growing stem cell). Inside the cell's mitochondria, cellular respiration breaks the glucose apart: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy for ATP. The carbon atoms leave as CO₂ — back into the atmosphere. The energy that was in the chemical bonds is now driving the cell's work (growing, repairing, moving). Again: no energy was created; the chemical energy was converted to other useful forms.

The conservation payoff: Every carbon atom in the plant was once in the air. Every hydrogen and oxygen atom was once in water. The plant is literally made of air and water, assembled by sunlight. When the plant is eaten (or dies and decomposes), those atoms return to the air, water, and soil — cycling through again. Nothing is lost.

Show me a matter-and-energy tracking table connecting all four weeks Tier 2 · organizer

Fill in this table to connect each week's idea to the model you will build:

Week 1 (cells as basic units): Every function in the model (photosynthesis, respiration, delivery) happens ________ cells. The structures that do photosynthesis are called ________; the structures that do respiration are called ________.

Week 2 (photosynthesis): Matter in: ________ + ________. Energy in: ________. Matter out (stored): ________. Matter out (released): ________. The mass of the plant comes mostly from ________ in the air, NOT from ________.

Week 3 (cellular respiration): Matter in: ________ + ________. Products: ________ + ________ + ________. The energy released is used for: ________, ________, and ________.

Week 4 (organ systems): In a plant, matter moves from leaf to roots through ________. In an animal, the ________ system delivers glucose and the ________ system delivers oxygen to every cell.

Conservation check: Add up all the atoms that entered the plant this week (CO₂ + H₂O). Are the same atoms still there in some form? Where are the carbon atoms that left as CO₂ during respiration? (Answer: they went back into the ________ — they were not destroyed.)

Performance task Model matter and energy in a living thing

This is the unit summative task. Use everything from Weeks 1–4. You may choose the windowsill plant OR your own body as your living system. Complete all four parts. All response modes are equally valid — draw a labeled diagram, write an explanation, or record yourself explaining it out loud.

🌿 I will model the windowsill plant 🧍 I will model my own body 🎨 Draw a labeled diagram + annotate ✍️ Write a paragraph explanation for each part 🗣️ Record yourself explaining step-by-step

Part 1 — Show where matter comes from and where it goes.

In your model (diagram or written), show or explain:

What specific molecules of matter does your living thing take in from the environment? (Name the molecules, not just "food" or "air.") Where does each one enter the organism?
What happens to those molecules inside the organism — are they broken down, rearranged, or built into new structures? Name at least one specific organelle or organ system involved in this transformation.
What molecules leave the organism as waste or byproduct, and where do they exit? Are those the same atoms that came in — just rearranged? Explain.

Conservation check: Point to one specific example in your model where you can show that matter was conserved — that atoms were rearranged but none were created or destroyed.

Part 2 — Show where energy comes from and how it is transformed.

Where does the energy that powers your living thing originally come from? (Trace it back as far as you can — even for an animal that eats food.)
Describe at least two energy transformations that happen inside the organism. Use the word transformation — and name the form of energy before and after each change.
What happens to energy that is released but not used for useful work? (Hint: think about what you feel after exercise, or why a running engine feels warm.)

Conservation check: Energy was not created in your model — it came from somewhere. Point to where the energy entered your system and show that it was transformed, not created.

Part 3 — Show how the organism's structure (from cells to organ systems) makes the matter and energy flow possible.

Name the level of organization — cell, tissue, organ, or organ system — where each key transformation in your model happens. For example: "Photosynthesis happens in leaf cells, specifically inside the chloroplast organelle."
Name at least one structural feature (an organelle, a tissue, or an organ) whose shape or arrangement is directly connected to its function in the matter/energy story. Explain the connection between structure and function.
What would stop working first if one key structure were removed or damaged? Trace the consequence through the model.

Part 4 — Design a fair-test investigation. (OR explain the van Helmont result.)

Choose ONE of the following:

Option A — Design an investigation: A student wonders whether a plant needs light, CO₂, or water most to grow. Design a fair test to find out which variable matters most for the plant gaining mass over two weeks. Name your independent variable (what you change), dependent variable (what you measure), and at least two controlled variables (what you keep the same). Predict the result you would expect and explain the prediction using photosynthesis.
Option B — Explain the van Helmont result: Jan van Helmont grew a willow tree for five years. The tree gained 75 kg. The soil lost only 57 grams. He concluded the mass came from water. Using your model from Parts 1–3, explain (a) what van Helmont got right; (b) what he got wrong and what evidence we now have that corrects it; (c) which molecules are the actual source of most of the plant's mass, and how photosynthesis explains this.

I want sentence frames and a model template Tier 2 · frames + template

Part 1 sentence frames (matter):

My living thing takes in ________ and ________ from the environment. These molecules enter through ________. Inside the organism, they are transformed by [photosynthesis / cellular respiration] (circle one) in the ________ organelle / organ. The molecules that leave as waste are ________ and ________, which exit through ________. The same atoms that came in are still present in the products — they were rearranged, not destroyed. For example, the carbon atoms from CO₂ are now in ________.

Part 2 sentence frames (energy):

The energy that powers my living thing originally comes from ________. First energy transformation: ________ energy → ________ energy (this happens during ________). Second energy transformation: ________ energy → ________ energy (this happens during ________). Some energy is released as ________ heat, which is why living things feel warm.

Part 3 sentence frames (structure & function):

The key transformation (photosynthesis / respiration) happens in the ________ (cell / tissue / organ / organ system). The structural feature that makes this possible is the ________, which is shaped / arranged to ________. If this structure were damaged, the first thing that would stop working would be ________, because ________.

Part 4 sentence frames (investigation — Option A):

My independent variable (what I change): ________. My dependent variable (what I measure): ________. Controlled variables: ________, ________. I predict that removing ________ will cause the least/most growth because, based on photosynthesis, ________ is needed to ________.

Word bank: matter · energy · atom · molecule · CO₂ · H₂O · glucose · oxygen · chloroplast · mitochondrion · photosynthesis · cellular respiration · chemical energy · light energy · heat · cell · tissue · organ · organ system · circulatory · respiratory · digestive · conserved · transformed · rearranged · reactant · product · stomata · chlorophyll · ATP · independent variable · dependent variable · controlled variable

Let's make it concrete first — guided model with analogies Tier 3 · re-teach

Analogy for conservation of matter (Week 2): Imagine you have a bucket of 100 LEGO bricks. You take them apart and rebuild them into a different shape. Do you have more bricks at the end? No — you have exactly the same 100 bricks, just arranged differently. Atoms work the same way. When a plant takes in 6 CO₂ molecules and 6 H₂O molecules and makes one glucose molecule, it uses exactly those carbon, hydrogen, and oxygen atoms — no new atoms appear, and no atoms disappear. Photosynthesis is like disassembling CO₂ and water LEGOs and reassembling them into a glucose LEGO.

Analogy for conservation of energy (Week 3): Imagine a wound-up spring (stored/chemical energy). When you release it, the spring pushes something (mechanical/kinetic energy). The energy changed form — it was not created. The sun's energy → glucose's chemical energy → ATP's chemical energy → cell work. Each arrow is an energy transformation; the total energy is conserved (some becomes heat that is not useful, but it still exists).

Guided model for the plant — fill in the blanks:

Part 1 — Matter in: CO₂ from the air enters through stomata on the leaf. H₂O from the soil enters through the roots. Inside the leaf cell's chloroplast, photosynthesis joins them into glucose. Waste product: O₂ is released through the stomata. The carbon atoms that were in CO₂ are now in ________ (glucose). They were not created — they moved from the air into the plant.

Part 2 — Energy: The energy originally came from the sun (sunlight). First transformation: light energy → chemical energy (stored in glucose bonds — this is photosynthesis). Second transformation: chemical energy (glucose) → usable cell energy (ATP) + heat (this is cellular respiration). The energy was not created — it came from the sun.

Part 3 — Structure: Photosynthesis happens in leaf cells, inside the chloroplast. Respiration happens in every cell, inside the mitochondrion. The structure that makes it possible: chlorophyll in the chloroplast absorbs sunlight. If the chloroplasts were removed, photosynthesis would stop, glucose would not be made, and cellular respiration would eventually run out of fuel.

Once you have the blanks filled in, try saying each part out loud before writing it in your own words.

Push my thinking — open modeling with constraints and system thinking Extension

Quantitative matter trace: A glucose molecule has the formula C₆H₁₂O₆. Write the full equation for photosynthesis (6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂). Count the atoms on each side of the arrow. Do the numbers of each element (C, H, O) match? Now write the full equation for cellular respiration. Do the atom counts balance again? Explain in one sentence what the balancing of atoms in a chemical equation tells you about the conservation of matter.

Systems-level analysis: Trace a single carbon atom through the following journey: (1) it is part of a CO₂ molecule in the air; (2) a leaf absorbs it during photosynthesis; (3) the glucose is used by a root cell during cellular respiration; (4) the CO₂ is released back into the soil air. Then extend the trace: what other organisms might take in that same carbon atom next? How does this connect to the Energy & Matter throughline from the very first unit (Unit 1)?

Model limitation analysis: Every model has limitations. Identify two things your matter-and-energy model does NOT show or gets wrong. For each limitation, explain (a) what is left out or oversimplified, and (b) what data or evidence you would need to make the model more accurate.

Comparative investigation design: You want to test whether a plant's rate of photosynthesis is limited more by CO₂ concentration, light intensity, or water availability. Design an experiment with three separate conditions (one per variable). Name your independent variable, dependent variable (how you will measure photosynthesis rate — think about oxygen bubbles produced, glucose produced, or mass gained), and at least three controlled variables. Predict which variable is most limiting for a plant living in a dim indoor room — and justify using the photosynthesis equation.

How your work will be evaluated — the 3D rubric

Read this before you model. The strongest response connects all three dimensions — science practices, the core life-science ideas, and the crosscutting concept of Energy & Matter.

Performance Task Rubric — Unit 5 Capstone (MS-LS1-6 · MS-LS1-1 · MS-LS1-2 · MS-LS1-3)

Dimension	Emerging — getting started	Developing — on the way	Proficient — you've got it	Advanced — you're going beyond
SEP: Developing & Using Models · Constructing Explanations	A diagram or description is attempted but is incomplete — missing key components (e.g., no energy path, or matter enters but does not leave); model parts are not labeled or connected; no conservation check attempted.	Model shows at least one complete pathway (e.g., matter in → transformation → matter out, or energy in → transformation → energy used); some labels are present; conservation is mentioned but not demonstrated with a specific example from the model.	Model clearly shows both matter and energy pathways through the organism; both photosynthesis and cellular respiration are represented with correct reactants and products; at least one specific structural feature (organelle or organ) is labeled and its function is explained; a conservation check names a specific example of matter or energy being transformed rather than created.	Model is precise, complete, and multi-level (cell → organ system); quantitative detail is included (e.g., atom counts, specific molecules, chemical equations); model limitations are identified and explained; the investigation design (Part 4) includes all required variables and a justified, mechanistic prediction.
DCI: LS1.C Matter & Energy Flow · LS1.A Structure & Function · LS1.B Growth & Development	Names photosynthesis or cellular respiration but does not correctly describe reactants and products; may have a key misconception (e.g., "plants get energy from soil" or "energy is created by the mitochondria"); organ systems are not connected to matter/energy delivery.	Correctly describes photosynthesis OR cellular respiration (not both); connects one organelle to its function; mentions that organ systems deliver matter but does not explain how the delivery supports cellular respiration at the level of individual cells.	Correctly describes both photosynthesis (CO₂ + H₂O + light → glucose + O₂) and cellular respiration (glucose + O₂ → CO₂ + H₂O + energy); explains how cells use that released energy for life processes; connects at least one organ system (or vascular tissue in a plant) to the delivery of matter or removal of waste so individual cells can function; structure of at least one organelle is connected to its function.	Integrates all three DCI components: correctly describes photosynthesis and respiration at the molecular level (reactants, products, energy form changes); explains how multicellular organization (tissues, organs, systems) solves the problem of delivering matter and energy to every cell; traces a specific molecule (e.g., a carbon atom) from environment through organism and back; connects to the year's Energy & Matter throughline (Unit 1 onward).
CCC: Energy & Matter — matter is conserved; energy is transformed, not created	Does not address conservation; describes matter or energy as appearing from nowhere (e.g., "the plant makes energy from sunlight" without explaining the transformation) or disappearing (e.g., "the carbon just goes away"); matter and energy treated as interchangeable or confused.	Acknowledges that matter is conserved in general terms ("atoms don't disappear") but does not trace specific atoms or molecules through the model; or acknowledges energy transformation but conflates transformation with creation ("the plant makes new energy in the chloroplast").	Explicitly shows that matter is conserved: names specific molecules that enter, where their atoms go (stored in glucose, released as CO₂/H₂O), and that the same types of atoms are present before and after each transformation; explicitly shows that energy is transformed rather than created: traces the energy from sunlight → chemical bonds in glucose → released energy for cell work → heat; does not confuse transformation with creation at any point.	Demonstrates conservation at the atomic/molecular level using chemical equations (atoms balance on both sides); traces a specific atom (e.g., one carbon) through the full cycle (air → glucose → CO₂ → air); explains what happens to energy that becomes heat (it still exists but is no longer useful for cell work — it disperses into the surroundings); connects conservation to the larger carbon cycle and the year's Energy & Matter throughline.

Check yourself Unit synthesis — did it connect?

Success criteria — I can:

describe what molecules enter and leave a living thing, and explain that the atoms in those molecules are conserved — rearranged but never created or destroyed;
explain how sunlight energy is captured by photosynthesis and stored in glucose, then released by cellular respiration — and that energy is transformed, not created;
connect cell structures (chloroplast, mitochondrion) to their roles in matter and energy transformation;
explain how organ systems in a multicellular organism deliver matter and remove waste so that every cell can carry out cellular respiration;
trace the unit's Energy & Matter throughline: a plant's mass comes from CO₂ and H₂O, assembled by sunlight — not from soil.

A student models the windowsill plant. She draws an arrow showing energy flowing INTO the plant from sunlight, and another arrow showing new energy being MADE inside the mitochondrion during cellular respiration. Her teacher says the second arrow is incorrect. What should the model show instead — and why?

Re-teach: matter and energy are conserved — they cannot be created or destroyed, only transformed Tier 3

The key idea from the year's Energy & Matter throughline: Matter and energy cannot appear from nowhere or disappear into nowhere. They can only change form or move from place to place.

For matter: When a plant makes glucose during photosynthesis, the carbon atoms in the glucose came from CO₂ molecules in the air. They were rearranged — not created. When cellular respiration breaks glucose apart, those same carbon atoms leave as CO₂ — they were not destroyed. If you count every carbon, hydrogen, and oxygen atom at the start and end of either reaction, the numbers must match exactly. This is conservation of matter.

For energy: The energy that drives all life processes in the plant originally came from sunlight. The chloroplast captured that sunlight energy and stored it in the chemical bonds of glucose (light energy → chemical energy — this is photosynthesis). The mitochondrion later breaks those bonds, releasing the already-stored energy (chemical energy → ATP energy + heat — this is cellular respiration). At no point did new energy appear. The mitochondrion is an energy releaser, not an energy maker. The same is true for your body: every calorie you burn came ultimately from the sun, via the plants and animals you ate.

Common mistake to avoid: saying "the mitochondrion makes energy" or "the plant uses sunlight to make energy." Both phrases imply energy was created. Instead say: "the mitochondrion releases stored energy" and "the plant captures and stores sunlight energy in glucose." Energy changes form; it is never made from nothing.

Now re-read option B. It describes this correctly. Try explaining the energy chain (sun → glucose → cell work) in your own words before moving on.

Reflect, then show what you know

Metacognitive reflection metacognition + SEL

Answer at least one:

What is one idea from this unit that surprised you — something that contradicted what you thought you knew before Week 1? What changed your mind?
Which of the four weeks felt most connected to your daily life? Describe a specific moment in your day when one of the unit's ideas (cells, photosynthesis, respiration, organ systems) was happening in your body or the world around you.
If you had to explain to a younger student why "a tree is made of air" — without using the word photosynthesis — what would you say? Write two to three sentences.

Self-assessment against the rubric responsible decision-making

Look back at the 3D rubric. For each row (SEP, DCI, CCC), write the level that best describes your performance task response — Emerging, Developing, Proficient, or Advanced. Then write one specific thing you would add or change to move up one level.

SEP (Developing & Using Models): I am at _______________. One thing I would add: _______________.

DCI (Matter & Energy Flow, Structure & Function): I am at _______________. One thing I would add: _______________.

CCC (Energy & Matter — conservation): I am at _______________. One thing I would add: _______________.

One revision: Based on your self-assessment, go back to your model and make one specific addition or correction. Write here what you changed and why.

I changed: _______________ because _______________.

Transfer item transfer to a new context

A student claims: "A compost pile turns food scraps into soil — so matter is created in a compost pile, since you start with garbage and end up with rich soil." Using the Energy & Matter CCC and what you know about matter conservation, explain what is actually happening in a compost pile. Where does the mass of the food scraps go? Are new atoms created? What happens to the carbon atoms in the scraps?

In a compost pile, the matter from food scraps is not created or destroyed. Instead, _______________. The carbon atoms in the scraps _______________. This is similar to what happens in a plant because _______________.

Exit ticket — answer on paper or in your notebook. (2 new · 2 spiral · 1 transfer)

New A student says: "The plant's chloroplasts make energy from sunlight." Rewrite this sentence to correctly describe what is happening, using the words capture, transform, and store.
New Write the word equation for photosynthesis. Circle the reactants. Underline the products. Put a star next to the form of energy that enters and the form that is stored. Explain in one sentence how this equation shows conservation of matter.
Spiral — Week 2 Jan van Helmont's experiment showed that a willow tree gained 75 kg while the soil lost only 57 grams. He concluded the mass came from water. Name the actual source of most of the tree's additional mass, and explain using photosynthesis why his conclusion was incomplete.
Spiral — Week 3 A plant is kept in the dark for two weeks. It has plenty of water and soil, but no light. Predict what will happen to the plant and explain your prediction by tracing what happens to (a) glucose availability and (b) cellular respiration in the plant's cells.
Transfer You eat a peanut butter sandwich. The peanut butter contains fats and proteins that originally came from peanut plants. Trace the energy in that sandwich all the way back to its original source. Then trace one carbon atom from the air to your leg muscle. At each step, name the process that moved or transformed the matter or energy, and confirm that matter and energy were conserved at each step — not created.

Educator panel — facilitation, accommodations, rubric guidance, answer key, research rationale

At a glance

Primary standard: NGSS MS-LS1-6 — Construct a scientific explanation based on evidence for the role of photosynthesis in the cycling of matter and the flow of energy into and out of organisms. Integrated standards: MS-LS1-1 (conduct an investigation to provide evidence that living things are made of cells; cells need food for energy; they provide for all of a living thing's needs); MS-LS1-2 (develop and use a model to describe the function of a cell as a whole and ways parts of cells contribute to the function); MS-LS1-3 (use argument supported by evidence for how the body is a system of interacting subsystems composed of groups of cells). 3D lens: SEP Developing & Using Models + Constructing Explanations · DCI LS1.C Organization for Matter and Energy Flow + LS1.A Structure and Function + LS1.B Growth and Development · CCC Energy and Matter — matter is conserved; energy is transformed, not created.

Materials needed: None required beyond paper and pencil. Optional enhancements: a real plant (the "windowsill plant" that may have been observed throughout the unit), a brief demonstration of yeast + sugar + warm water producing CO₂ bubbles (visualizes cellular respiration in real time), or a CO₂ sensor if available (shows that breathing and plants respire). None are required; the lesson works fully with the SVG diagram and written scenario.

Estimated time: 60 minutes. Parts 1–3 of the performance task take 25–30 minutes for most learners. Budget time for rubric self-assessment and the transfer item. The exit ticket can be assigned for homework if the period runs short. The Do-Now (retrieval) should not be skipped — it activates the four-week schema before students begin the synthesis task.

Facilitation arc (Rosenshine + storyline pedagogy)

Do-Now retrieval (6 min) — students work individually; do not provide answers yet. Cold-call one student per question; probe with "How do you know?" to surface reasoning, not just recall. Write key vocabulary from their answers on the board (photosynthesis, cellular respiration, glucose, CO₂, H₂O, chloroplast, mitochondrion, organ system) — they will need it for the task.
Phenomenon + notice/wonder (5 min) — display the SVG. Give 60 seconds of silent noticing. Ask: "Where in this diagram do you see something from Week 2? Week 3? Week 4?" The goal is to activate the unit arc before synthesis. Write two to three "wonder" questions on the board.
Synthesis build + worked example (8 min) — read "Tie it together" as a class. Use think-pair-share on this question: "The worked example says a plant is made of air. What does that mean — and how is it possible?" Then walk through Steps 1–3 of the worked example. Ask: "At what step did matter get conserved? At what step did energy get transformed?" This bridges prior learning to the performance task.
Introduce the performance task + rubric (4 min) — read the rubric aloud together before students begin. Ask: "What would a Proficient response include in the DCI row? What would make it Advanced?" Emphasize that a labeled diagram counts as much as a written paragraph. Let students choose their living system (plant or self) and response mode.
Performance task (22–25 min) — students work independently or in pairs. Circulate and ask probing questions: "Where did the energy in that glucose come from?" "What happened to the carbon atoms after respiration?" "How does the organ system you named connect to a single leaf cell?" Do not give answers — ask questions that push students toward their own reasoning. Prompt students who finish early to attempt Part 4 Option B (van Helmont) or the Extension.
Self-check + re-teach (4 min) — take a quick poll (A/B/C/D). Route all non-B responders to the re-teach panel. Briefly explain the energy transformation chain to the whole class before moving to reflection — this is the most common and most consequential misconception in the unit.
Brain break + reflection + exit ticket (10 min) — the brain break connects respiration to the student's own breathing; it reinforces the CCC in a kinesthetic way. The transfer item (compost pile) is well-suited for a think-pair-share before the individual exit ticket.

IEP / 504 accommodation cards

Common accommodations mapped to this lesson

Accommodation	How it's already built in / what to do
Text read aloud	Every passage has a Listen button (TTS via Web Speech API); the simplified text toggle shortens all passages throughout the lesson.
Reduced reading load	"Reading: Simplified" swaps in plain-language text for all core passages; the Tier-3 support panel provides guided fill-in-the-blank prompts instead of open-ended writing.
Chunking / extended time	The performance task is broken into four clearly numbered parts; each part is self-contained; progress saves automatically to localStorage so students can work across multiple sessions.
Sentence frames / word bank	Tier-2 support panel provides complete sentence frames for all four parts and a 30-term word bank.
Concrete analogy / reduced load	Tier-3 panel provides the LEGO-bricks analogy for matter conservation and the wound-up spring analogy for energy transformation; guided fill-in-the-blank prompts walk through the plant model step-by-step with minimal open-ended writing.
Alternative response mode	Students may draw a labeled diagram, write paragraphs, or record a verbal explanation — all three are explicitly accepted as equally valid throughout the task.
Behavior / focus (504, ADHD)	Named PBIS expectations at the start, a 30-second SEL check-in, the 90-second kinesthetic brain break (deep breathing / respiration connection), and four short numbered parts with visible progress.
Multilingual / EL	Simplified text toggle, the annotated SVG diagram (visual with labeled components), word bank in Tier-2, home-language reflection allowed in the metacognitive prompts, cognate-friendly vocabulary (photosynthesis/fotosíntesis, respiration/respiración, cell/célula, molecule/molécula).
IEP goal: written expression	Accept a fully labeled diagram (Parts 1–3) with minimal annotation as a complete response; oral explanation to the teacher is also accepted. The Tier-3 fill-in-the-blank version reduces the written expression demand while maintaining the conceptual goal.
IEP goal: science reasoning	The rubric's Emerging and Developing descriptors define the scaffolded floor — any response that correctly names photosynthesis or cellular respiration with at least one reactant and product is gaining in the right direction. The Tier-3 guided-choice panel sets a concrete floor for success while targeting the same standard.

Rubric scoring guidance + exemplar response sketch

What a Proficient response looks like (windowsill plant):

SEP: "I drew the plant with labeled arrows showing CO₂ and H₂O going into the leaf (photosynthesis inputs), glucose and O₂ coming out, glucose traveling to cells, and CO₂ and H₂O leaving cells during respiration. I labeled the chloroplast (photosynthesis) and the mitochondrion (respiration). For the conservation check, I traced the carbon atom from CO₂ in the air → into glucose → out as CO₂ during respiration — the same atom, just rearranged. For Part 4, I designed a fair test: independent variable = light (present vs. absent); dependent variable = mass gained over 2 weeks; controlled variables = CO₂ level, water amount, temperature, same-starting-mass plants."
DCI: "Photosynthesis: CO₂ + H₂O + light → glucose + O₂. This happens in the chloroplasts of leaf cells. Cellular respiration: glucose + O₂ → CO₂ + H₂O + energy. This happens in the mitochondria of every cell. The plant's vascular tissue (xylem and phloem) delivers water from roots to leaves and glucose from leaves to roots — this is how the cells that can't do photosynthesis (like root cells) still get the glucose they need for respiration."
CCC: "The carbon atoms in the plant's body came from CO₂ in the air — they were rearranged by photosynthesis, not created. The energy came from sunlight — it was transformed into chemical energy stored in glucose bonds (photosynthesis), then transformed again into usable energy for cell work (respiration). No energy was made by the mitochondrion — it released energy that was already stored. Matter and energy are conserved at every step."

Common errors to address:

"Plants get their mass from soil" — redirect to Week 2 (van Helmont experiment); the soil loses almost no mass while the plant gains kilograms; the mass comes from CO₂ in the air, rearranged by photosynthesis. This is the unit's central misconception correction.
"The mitochondrion makes energy" or "cells create energy" — redirect to the CCC: energy cannot be created. The mitochondrion releases energy that was stored in chemical bonds. Prompt: "Where did the energy in the glucose come from?" (Answer: the sun, via photosynthesis.)
"Photosynthesis and cellular respiration are opposites that cancel out" — they are complementary, not canceling. Photosynthesis stores energy in glucose; respiration releases it. The plant uses both, often simultaneously (respiration runs in all cells all the time; photosynthesis runs in green cells with sufficient light).
Confusing oxygen as an energy source — prompt: "Is O₂ matter or energy? What role does O₂ play in cellular respiration? (It's a reactant — a matter input — not the energy source; the energy is stored in glucose bonds.)"

Exit ticket answer key

Corrected sentence: "The plant's chloroplasts capture light energy from sunlight, transform it into chemical energy, and store that chemical energy in the bonds of glucose molecules." (Key: capture/transform/store instead of "make energy.")
Photosynthesis equation: CO₂ + H₂O + [light energy] → glucose + O₂. Reactants (circled): CO₂, H₂O. Products (underlined): glucose, O₂. Energy starred: light energy enters; chemical energy is stored in glucose. Conservation of matter: the same carbon, hydrogen, and oxygen atoms present in the reactants appear in the products — the numbers and types of atoms are the same on both sides of the arrow; no atoms were created or destroyed.
Most of the tree's additional mass came from carbon dioxide (CO₂) in the air. During photosynthesis, carbon atoms from CO₂ are bonded into glucose molecules (C₆H₁₂O₆). Over time, the tree builds those glucose molecules into cellulose, starch, and other organic molecules that make up its wood, leaves, and roots. Van Helmont was correct that water is a reactant (H₂O provides hydrogen and oxygen atoms), but he overlooked the much larger contribution of CO₂ from the air as the source of carbon atoms that form most of the plant's mass.
A plant kept in the dark for two weeks will slowly wither and die. Without light, photosynthesis cannot occur — the chloroplasts have no energy source to convert CO₂ and H₂O into glucose. The plant's glucose stores are gradually depleted as every cell in the plant continues to run cellular respiration (which never stops — cells always need energy). When glucose runs out, respiration slows, the cell can no longer do the work it needs to do (maintain membranes, repair proteins, grow), and cells begin to fail. The plant wilts and eventually dies.
Energy trace — peanut butter sandwich: Peanut plant leaves captured sunlight energy via photosynthesis → stored as chemical energy in glucose → converted to starch, fats, and proteins in the peanut → eaten by you → digested into glucose and fatty acids → transported by the circulatory system to muscle cells → cellular respiration in muscle cell mitochondria converts glucose + O₂ → CO₂ + H₂O + energy used to contract the muscle. At every step, energy was transformed (light → chemical → chemical → kinetic + heat), never created. Matter trace — one carbon atom: CO₂ molecule in air → absorbed through leaf stomata during photosynthesis → bonded into glucose (C₆H₁₂O₆) → stored in peanut oil or protein → digested and absorbed into bloodstream → transported to muscle cell → broken down during cellular respiration → released as CO₂ through exhalation. The atom was rearranged at every step; it was not created or destroyed.

Why it's designed this way — research rationale

Why the matter-conservation payoff is the performance task's center: Research on science misconceptions consistently identifies "plants get their food from soil" and "cells make energy" as among the most persistent errors in middle-school life science (Driver et al., 1994; Anderson et al., 1990). MS-LS1-6 specifically asks students to construct an explanation for the role of photosynthesis in the cycling of matter and the flow of energy — meaning students must be able to trace atoms (not just name the process) and distinguish transformation from creation. The van Helmont Option in Part 4 directly confronts the soil misconception with historical evidence, a strategy shown to be more durable than simply stating the correct fact (Limon, 2001).

Why a model, not a recall test (NRC, 2012; Schwarz et al., 2009): Models are a core NGSS science practice because they make thinking visible. A student who draws a matter/energy pathway through an organism — with labeled reactants, products, and transformation steps — has demonstrated understanding at a level that a multiple-choice question about "the reactants of photosynthesis" cannot assess. The three response modes (diagram, paragraph, recording) reflect UDL's multiple means of expression (CAST, 2024): the cognitive goal (modeling matter/energy flow) is invariant; the medium of expression is flexible.

Why interleaved retrieval in the Do-Now (Roediger & Karpicke, 2006; Rohrer, 2012): One item per prior week ensures that all four conceptual building blocks are active in working memory before students attempt the synthesis task. This is especially important for the CCC: a student who cannot recall that photosynthesis stores sunlight in glucose (Week 2) will not be able to correctly represent the energy transformation chain in the model. The Do-Now is not a quiz — it is a retrieval-priming warm-up that reduces the cognitive load of the synthesis task by activating prior schemas.

Why the CCC "Energy & Matter" is the self-check's focus: The self-check targets the most common and most consequential misconception (mitochondria make energy, not release it) because this is the error most likely to persist after instruction if it is not directly addressed. The branching routes A, C, and D each represent a distinct but wrong path, allowing the educator to diagnose the specific nature of the misconception (over-reliance on the "bright light" shorthand; confusion of matter-to-energy conversion; incomplete tracing of the energy chain). The re-teach uses the wound-up spring analogy, which externalizes the concept of stored and released energy in a concrete, accessible form (van Merriënboer & Sweller, 2005).

Strengths-first rubric design (Black & Wiliam, 1998; Wiliam, 2011): The rubric labels levels as Emerging through Advanced — not Failing or Insufficient. Each descriptor names what to do next. The Emerging descriptor for the DCI row explicitly lists the most common misconception ("plants get energy from soil") so students can self-diagnose. The Advanced descriptor sets a visible reach target (balanced chemical equations, carbon cycle tracing) without requiring it for Proficient. Pre-task rubric reading is one of the highest-impact formative practices (Wiliam, 2011, p. 127) and is built into the facilitation arc.

The Energy & Matter throughline (NGSS Appendix G): This unit is designed as the payoff of the year's CCC: Unit 1 introduced where energy goes (hand warmers, cocoa cooling); Units 2–4 built understanding of energy and matter flows in physical and Earth systems; Unit 5 completes the arc by showing that the same conservation principles apply inside living things. The transfer items — the compost pile, the peanut butter sandwich — are designed to require students to apply this CCC to contexts they have not seen in class, testing genuine transfer rather than retrieval of a memorized example.

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