What Makes a Cell Work?
Modeling how a cell's parts keep it alive
Original portfolio sample created to demonstrate design capability. Not affiliated with or produced for any employer or institution. NGSS performance-expectation wording is quoted from the public standard; supporting-standard text is paraphrased and marked as such.
Standards Alignment
Verbatim: “Develop and use a model to describe the function of a cell as a whole and ways the parts of cells contribute to the function.”
Paraphrased: conduct an investigation to provide evidence that living things are made of cells, either one cell or many. Establishes the cell as the unit of life this unit models.
Scope boundary (per MS-LS1-2 assessment boundary): this unit does not address the cell cycle, cell division, or the biochemistry of cell processes.
5E Lesson Flow
Students sketch their current model of a single cell: what is inside it and what each part might do, from memory. The teacher surfaces the driving question, “A single cell is alive on its own. How do its parts work together to keep the whole cell alive?” and lists the jobs any living thing must do (take in materials, release energy, remove waste, build parts, follow instructions) without yet naming which part does each.
Structure-to-function modeling activity. In pairs, students receive part cards (each with a labeled image and a structure clue) and “cell jobs” cards. Using the structure–function table (student handout, below), they match each part to the job its structure lets it do, then assemble a labeled model of the cell and draw arrows showing which parts depend on one another. Functions are inferred from structure clues, not front-loaded as a vocabulary list.
A teacher-led discussion formalizes the structure→function links students built: the membrane controls what enters and leaves, the nucleus stores instructions and directs activities, mitochondria release energy from food, ribosomes build proteins, and the cytoplasm holds the parts where activities happen. Students revise their model with accurate labels and correct any mismatched arrows.
Given a “what if this part stopped working?” scenario: for example, the membrane can no longer control what passes through, students use their model to predict the effect on the whole cell and mark which other parts would be affected. This extends the model from parts to system-level cause and effect.
A formative exit ticket checks the core idea; a summative, model-based CER prompt (below) asks students to use their model to explain how the parts of a cell work together to keep the whole cell alive.
Teacher Guide
Two 50-minute sessions. Session 1: Engage + Explore. Session 2: Explain + Elaborate + Evaluate. Explore is the anchor: protect its full 30 minutes for building and revising the model.
- Labeled animal- and plant-cell diagrams (illustrative)
- Part cards + “cell jobs” card sets (one per pair)
- Structure–function reference table (one per student)
- Blank cell-outline model template
- CER organizer + exit-ticket slips
Clarify: a cell is highly organized, each part has a specific structure and job, and the parts work together as a system.
Clarify: the nucleus stores instructions and directs activities, but no part “thinks”, parts carry out physical and chemical processes, not decisions.
Clarify: they share most parts; plant cells add a cell wall and chloroplasts and usually a large central vacuole.
Emerging readers: provide the structure–function table with the functions in a word bank; pair each part with its labeled image and give sentence starters (“The ___ helps the cell by ___.”).
Advanced extension: ask students to identify the one part whose failure would affect the most others, and defend the choice using their model's arrows, bridging toward systems thinking.
Student Handout
A single cell is alive on its own. How do its parts work together to keep the whole cell alive?
| Cell part | What it looks like (structure) | What it does (function) |
|---|---|---|
| Cell membrane | Thin, flexible outer boundary around the cell | Controls what enters and leaves the cell |
| Nucleus | Large, round structure near the center | Stores the cell's instructions and directs its activities |
| Cytoplasm | Jelly-like fluid that fills the cell | Holds the parts in place; where many activities happen |
| Mitochondria | Small, bean-shaped structures | Release energy from food for the cell to use |
| Ribosomes | Tiny dot-like structures throughout the cell | Build the proteins the cell needs |
| Vacuole | Fluid-filled sac (large in plant cells) | Stores water, food, and waste |
| Cell wall (plant) | Rigid layer outside the membrane | Supports and protects the cell; gives it shape |
| Chloroplast (plant) | Green, oval structures | Capture light energy to make food for the plant cell |
- Choose two parts. For each, explain how the whole cell would be affected if that part stopped doing its job.
- Several parts work together so the cell has usable energy and the proteins it builds. Which parts are involved, and what is each one's role?
- A cell is a system, its parts depend on one another. Pick one part, name another part it depends on, and explain why.
Assessment
“Name one cell part and, in one sentence, explain how its job helps keep the whole cell alive.” Quick to read; tells the teacher whether the structure→function link landed before Session 2 ends.
“Use your labeled model to make a claim about how the parts of a cell work together to keep the whole cell alive. Support it with evidence: specific parts and their jobs from your model, and explain your reasoning for how the parts depend on one another as a system.”
MS-LS1-2 is a modeling standard, students build, use, and revise a model rather than label a diagram once, making structure→function→system reasoning visible and assessable.
Inferring function from a structure clue means the vocabulary attaches to reasoning students did themselves, directly targeting the Structure & Function crosscutting concept.
Treating the cell as interdependent parts addresses the “cell as a whole” half of the PE and sets up later body-systems units.
Content stays inside the MS-LS1-2 boundary (no cell cycle, division, or biochemistry) and would be reviewed with a subject-matter expert before classroom release.