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# Is everything alive made of cells?

Year 8 Biology · Cells

<!-- Speaker note: Students state cell theory, explicitly including plants, fungi and single-celled organisms, and distinguish single-celled from multicellular organisms (AC9S8U01, node 2, a hinge node). About 20 minutes (Engage and Explore 7 min · Explain 7 min · Evaluate 3 min · Typical adds 2 min, Wider about 2 min). -->

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## Today

**We are learning to** cell theory: all living things, including plants, fungi and bacteria, are made of cells. Some organisms are a single cell; others are made of many.

- I can state cell theory.
- I can explain that plants, fungi and bacteria are made of cells too.
- I can give examples of single-celled and multicellular organisms.

<!-- Speaker note: Before class: A concept tutorial for introducing or revising the idea; it does not replace microscope work (onion skin, cheek cells, yoghurt bacteria). Set the width with `?width=minimum`, `typical` (default) or `wider`. The hinge misconception is that only animals have cells. The Explore step shows a bacterium and yeast before any animal cell. Board notes: diagrams are simplified models, not to scale; students click parts to name them, and a tick marks each found. -->

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## Why it matters

> A gum tree, a mushroom, the bacteria in yoghurt and you. One thing they share that a rock, a cloud and a robot don't.

<!-- Speaker note: In Year 3 you sorted living from non-living. This lesson gives the deeper reason. -->

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<span style="background:#dbeafe; color:#1a1a1a; border:1.5px solid #3b82f6; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">💬 Discussion</span>

## Engage: predict

**Which of these are made of cells?**

- Animals and plants
- Only things you can see moving
- Animals, plants, fungi and bacteria: every living thing
- Only animals

<!-- Speaker note: What happens: Every living thing: animals, plants, fungi and bacteria. A bacterium is a single cell; you are trillions of cells. Take two or three predictions before anyone runs it. -->

<!-- Speaker note: Teacher: count how many chose 'only animals' or 'animals and plants'. -->

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<span style="background:#fef3c7; color:#1a1a1a; border:1.5px solid #f59e0b; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✍️ Activity</span>

## Explore it

{{embed: https://studio.learningwaypoints.com/tutorials/_playground-board/index.html?id=deck%2Fscience%2Fbiology-8%2Fcells-everywhere%2Fstep-2&code=widget%3A+cell%0Ashow%3A+bacterium%2C+yeast%0Afind%3A+membrane%2C+cytoplasm%0A&fresh=1}}

[Open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/science/biology-8/cells-everywhere/?full=step-2#step-2)

<!-- Speaker note:  -->

<!-- Speaker note: Teacher: ask what every diagram had (membrane, cytoplasm). -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## What happened?

* Every living thing: animals, plants, fungi and bacteria. A bacterium is a single cell; you are trillions of cells.

<!-- Speaker note: Reveal after running. Ask who predicted it, and what made them think so. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Cell theory

**Which statement is cell theory?**

- Big organisms have big cells
- All living things are made of one or more cells, and the cell is the smallest unit of life
- Cells are found in living and non-living things
- Only animals are made of cells

* Answer: All living things are made of one or more cells, and the cell is the smallest unit of life

<!-- Speaker note:  -->

<!-- Speaker note: Teacher: the first question is the checkpoint; the sort includes the mushroom on purpose. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## One or many

**Single-celled or multicellular?**

Groups: Single-celled · Multicellular

Bacteria in yoghurt · Yeast · A gum tree · A mushroom · An amoeba · You

* Answer: Bacteria in yoghurt → Single-celled; Yeast → Single-celled; A gum tree → Multicellular; A mushroom → Multicellular; An amoeba → Single-celled; You → Multicellular

<!-- Speaker note:  -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Doing everything

**A single-celled yeast cell and one of your skin cells are both cells. What's the big difference?**

- The yeast cell does everything to stay alive on its own; your skin cell is one of trillions, each doing a job
- Your skin cell has no membrane
- The yeast cell isn't really alive

* Answer: The yeast cell does everything to stay alive on its own; your skin cell is one of trillions, each doing a job

<!-- Speaker note:  -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Elaborate: is it alive?

**Made of cells (living, or once living) or not?**

Groups: Made of cells · Not made of cells

A slice of bread · A wooden table · A pebble · A cotton T-shirt · Plastic

* Answer: A slice of bread → Made of cells; A wooden table → Made of cells; A pebble → Not made of cells; A cotton T-shirt → Made of cells; Plastic → Not made of cells

<!-- Speaker note: What this step is for: Using cells as the test for living sharpens the Year 3 distinction. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Elaborate: the smallest living thing

**A virus is far smaller than a bacterium. It has DNA (or RNA) in a protein coat, but no membrane or cytoplasm of its own, and it can only reproduce inside a living cell. Using cell theory, is a virus a living thing?**

- Yes: it has DNA
- Yes: it is very small
- By cell theory, no: it isn't a cell, so scientists usually call it non-living

* Answer: By cell theory, no: it isn't a cell, so scientists usually call it non-living

<!-- Speaker note: Viruses sit on the boundary. Most biologists say they are not alive, because they are not cells. What this step is for: Asking what the minimum for life is uses cell theory to reason about a boundary case. -->

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## Evaluate: look back

Write one sentence: "At first I thought… Now I think… because…"

**Revision summary**

- **Cell theory:** all living things are made of one or more cells; the cell is the smallest unit of life; cells come from other cells.
- That includes **plants, fungi and bacteria**, not only animals.
- **Single-celled** organisms (bacteria, yeast) are one cell doing everything; **multicellular** organisms are many cells working together.

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Exit ticket

**Name a single-celled organism and a multicellular one that isn't an animal.**

* For example: a bacterium (single-celled) and a gum tree or mushroom (multicellular).

<!-- Speaker note: Students answer on paper or a mini whiteboard before the reveal. Anyone who cannot answer needs the main idea again next lesson. Where this leads: Next: the parts every cell shares (node 3), then plant cells' extra parts (node 4). In class: onion epidermis with iodine and cheek cells with methylene blue under a microscope. -->