Cell Theory
Every living thing is built from tiny living units called cells.
Topic 1 of 5Grade 6 · Life Science
- Teacher:
- Mr. Mohamed Fawzy
- Site:
- Science with Mr. Fawzy
- Unit:
- From Cells to Ecosystems
- Version:
- 3.2
How this topic is built
- Covers workbook pages 61, 64 and 65 (Week 6: What is the Cell Theory, and the Organelle Structure & Function chart), plus the plant/animal Venn diagram activity as a sorting game.
- All text is rewritten in plain language; every fact from the workbook is kept, and scientific errors are corrected. Each correction has a note on its slide.
- Slides alternate Read, Look, Do and Check. Eleven Quick Checks, then an 8-question quiz at the end.
- Organelle spotlights (new in version 3): one slide for each of the 13 cell parts, with a short video and a Structure / Shape / Function card. Plan about one extra class period for them.
Video: From Body to Cell
About this video
An animated explainer, about 2 to 3 minutes. There is no sound: the words appear in the caption box under the picture, so you can read them aloud or let students read. Use the chapter menu to replay one part, and Speed to slow it down.
How to use it
- Pause after chapter 1 and ask: "Is a rock made of cells? Is your skin?"
- After chapter 3, have students say the three rules from memory before moving on.
- Zooming in (tissue, cell, organelle) and the traits of living things are not in the video, because each has its own slide: the zoom simulator and "What makes something alive?".
Full script
Cells: the building blocks of life
Get ready for a big idea: every living thing is made of cells. A cell is the smallest unit of a living thing, like one LEGO brick in a giant build.
You, your dog or cat, the tree your notebook paper came from, and even the bacteria living on your skin right now are all made of cells. Any single living thing is called an organism.
Unicellular (uni = one): the whole organism is just one cell. Most are too small to see without a microscope.
Multicellular (multi = many): the organism is made of many cells working together. You are multicellular.
Common mistakes
- Thinking only animals (or only people) are made of cells.
- Thinking bones, hair roots, or blood are "not cells".
- Thinking unicellular organisms have a tiny version of our organs.
Correction from the workbook
- The workbook says unicellular organisms "are very tiny." Most are microscopic, but not all: some single-celled algae can be several centimeters long. The slide says "most are too small to see."
- The workbook says bacteria are "crawling" on your skin. Bacteria don't crawl; the slide says "living on your skin."
Teaching tip
Hold up one LEGO brick and a finished LEGO model: brick = cell, model = multicellular organism, a single brick that moves around on its own = unicellular organism.
Quick Check 1
One cell or many? Choose an answer.
What this checks
Unicellular vs. multicellular, and the idea that every living part of the body is made of cells.
If many students pick A, remind them: the size of each cell doesn't matter, the number of cells does.
The Cell Theory: three rules
No matter what kind of organism it is, every living thing follows these three rules.
All living things are made of one or more cells.
To use this rule, we need to know what counts as "living." That's coming up on slide 6.
New cells come only from cells that already exist.
Cells divide to make new cells. They can't just pop up out of nowhere. Cells grow, divide, and multiply.
The cell is the smallest unit that is alive.
Cells have smaller parts called organelles: tiny structures inside a cell, each with a job. But an organelle can't survive on its own or make new living things. Only a whole cell can.
Corrections from the workbook
- Workbook rule C: "Cells are the smallest part of an organism." That's not accurate: organelles and molecules are smaller parts (the workbook itself says so in the next paragraph). The correct idea is that the cell is the smallest part that is alive. The slide uses that wording.
- Workbook rule B: "Cells divide to make new cells." It is correct, and it is kept. The slide adds the standard wording, "new cells come only from existing cells," because that is how the theory is usually stated on tests.
Common mistakes
- Believing organelles are little living things.
- Believing cells can form from nonliving matter (the old idea of "spontaneous generation").
Zoom in: where does "alive" stop?
A tissue is a group of similar cells working together. Zoom levels are approximate.
How to use it
- Start with the maple leaf and zoom all the way in. Ask at each step: "Is this alive on its own?" The answer flips to "no" after the cell level. That is rule 3.
- Then try pond water: there is no tissue level, because a paramecium is a whole organism made of one cell.
- Onion cells have no chloroplasts: the bulb grows underground, away from light. Good link to slide 12.
Accuracy notes
Magnifications are rounded. A school light microscope reaches about 400× to 1,000×; seeing inside an organelle needs an electron microscope.
Quick Check 2
Use the three rules of the Cell Theory.
What this checks
Rule 3: an organelle alone is not alive. Choice B is a trap built on the idea that mitochondria "make energy". They release energy only inside a living cell.
What makes something alive?
Rule 1 says living things are made of cells. To use it, we need to know what "living" means. All living things share these 8 traits. Tap each one.
Tap a trait to read about it.
Correction from the workbook
- The workbook lists "Eat Food." Plants don't eat; they make their own food from sunlight. The slide says "Use energy," which fits all living things, and explains that animals eat and plants make food.
Kept at the workbook's level (as requested)
"Reproduce," "Pass on genes," and "Adapt" each get one simple sentence, the same depth as the workbook's list.
Teaching tip
Play "Alive or not?" with a pencil, a seed, a flame, a cloud, and a mushroom. A seed is alive (it is resting); fire has several traits but no cells.
Quick Check 3
Use the 8 traits of living things.
What this checks
A living thing needs all the traits, not just one or two. Fire is the classic example that fools students.
Home experiment 1: is yeast alive?
Baker's yeast from the grocery store is made of living, unicellular organisms. Let's test whether they use food for energy.
Expected result
Bottle B (yeast + sugar) inflates its balloon clearly within 20 to 40 minutes. Bottle A may inflate a tiny bit (yeast packets contain a little stored food). Bottle C stays flat.
Why two controls
A shows living cells need food; C shows food alone does nothing without living cells.
Common mistake
Using very hot water: above about 130 °F the yeast cells die, and no bottle inflates. That result can become a teaching moment about living cells.
Map: inside an animal cell
Tap a part to see its name. Then open its slide to learn its structure, shape, and function.
How to use this map
Students tap a part to see its name, then open that organelle’s slide. Each organelle slide has its own video, Structure / Shape / Function card, and notes.
Workbook corrections
Each correction to the workbook chart (pages 64–65) is written once, in the teacher notes of that organelle’s slide.
Kept from the workbook
All the look-alike comparisons: egg, highway, pancakes/WiFi symbol, hot dog with mustard, soup, sports-drink pouch, rigatoni.
Meet the organelles
An organelle is a tiny part inside a cell that has its own job. For each one, you will learn three things:
- Structure: what it is made of.
- Shape: what it looks like, and where it sits.
- Function: its job in the cell.
Each organelle has a short video. Tap one to jump to it, or just press Next.
How to use the spotlights
- The next 13 slides each cover one organelle, with a video under one minute and a Structure / Shape / Function card.
- A Quick Check comes after every two organelles.
- Suggested pacing: about one class period for the animal-cell organelles and part of the next for the plant-only ones. Students can copy the cards into a three-column table (Structure, Shape, Function) as they go.
A note on the word "organelle"
Strictly, the cytoplasm and cell membrane are not organelles, but every cell has them, so they are included here, as in the workbook chart.
Cell membrane
Organelle 1 of 13- Structure
- Phospholipid bilayer with proteins embedded in it (some are channel proteins).
- Shape
- Thin, flexible layer around the whole cell.
- Function
- Semipermeable: controls what enters and leaves the cell.
Found in: Plant and animal cells
Nickname: a gatekeeper
Key words: Phospholipid = a fat molecule with a head and two tails; Bilayer = two layers; Semipermeable = lets some things through, not others
About this video
A short animated close-up, under one minute, with three chapters: where the organelle is, its structure and shape, and its function. There is no sound; the words appear in the caption box. The card beside the video lists the same terms.
How to use it
Pause after chapter 2 and ask: "Why can water pass but not everything else?" The two layers of fat block many things; protein channels let chosen things through.
Correction from the workbook chart
The workbook says the membrane is "hydrophobic" and "repels water," and that semipermeable means it repels water. The membrane is a phospholipid bilayer that water passes through; semipermeable means it lets some things through and blocks others.
Common mistake
Plant cells have a membrane and a wall; the wall does not replace the membrane.
Full script
Cytoplasm
Organelle 2 of 13- Structure
- Cytosol (water, salts, sugars, proteins) + cytoskeleton (protein fibers).
- Shape
- Jelly-like; fills the cell around the organelles.
- Function
- Holds the organelles in place; many chemical reactions happen here.
Found in: Plant and animal cells
Nickname: the soup of the cell
Key words: Cytosol = the liquid part of the cytoplasm; Cytoskeleton = a network of protein fibers
About this video
A short animated close-up, under one minute, with three chapters: where the organelle is, its structure and shape, and its function. There is no sound; the words appear in the caption box. The card beside the video lists the same terms.
How to use it
The cytoskeleton is an extra term not in the workbook; it explains why the cytoplasm is not just "empty jelly." Students only need to recognize the word.
Common mistake
Students often draw the cytoplasm as empty space. It is packed with water, dissolved materials, and fibers.
Full script
Quick Check 4
Think about the edge of the cell.
What this checks
Which part controls movement into and out of the cell. Choice D catches students who think every cell has a wall.
Nucleus
Organelle 3 of 13- Structure
- Nuclear envelope (double membrane) with nuclear pores; contains chromatin (DNA) and the nucleolus.
- Shape
- Round; the largest organelle in an animal cell.
- Function
- Control center: stores the DNA. The nucleolus makes ribosomes.
Found in: Plant and animal cells (usually one per cell)
Nickname: the "brain" of the cell
Key words: Nuclear pore = a hole in the envelope; Chromatin = DNA in thin threads; Nucleolus = dark spot inside the nucleus
About this video
A short animated close-up, under one minute, with three chapters: where the organelle is, its structure and shape, and its function. There is no sound; the words appear in the caption box. The card beside the video lists the same terms.
How to use it
Link chapter 3 to Topic 2: the DNA threads shown here are the same material that forms chromosomes before a cell divides.
Common mistake
Students often think the nucleus builds proteins. It stores the instructions; ribosomes do the building.
Full script
Ribosomes
Organelle 4 of 13- Structure
- Two subunits (large + small) made of rRNA and protein. No membrane.
- Shape
- Tiny dots: free in the cytoplasm or attached to the rough ER.
- Function
- Protein synthesis: reads mRNA and joins amino acids into a protein.
Found in: Plant and animal cells (thousands in each cell)
Nickname: the factory of the cell
Key words: Subunit = one of the two parts; mRNA = a copy of a gene’s instructions; Amino acids = the building blocks of proteins
About this video
A short animated close-up, under one minute, with three chapters: where the organelle is, its structure and shape, and its function. There is no sound; the words appear in the caption box. The card beside the video lists the same terms.
How to use it
Pause in chapter 3 and compare: mRNA is the recipe, amino acids are the ingredients, the ribosome is the cook.
Correction from the workbook chart
The workbook says DNA’s directions are "translated by mRNA." mRNA carries a copy of the directions; the ribosome reads (translates) it.
Common mistake
Because ribosomes are so small, students skip them. Remind them that every cell, even a bacterium, has ribosomes.
Full script
Quick Check 5
Think about structure: what ribosomes are made of and where they are.
What this checks
Ribosome structure and location. Choice B catches students who confuse where ribosome parts are made (nucleolus) with where ribosomes work.
Endoplasmic reticulum (ER)
Organelle 5 of 13- Structure
- Network of membrane sacs and tubes, joined to the nuclear envelope. Rough ER: ribosomes attached. Smooth ER: no ribosomes.
- Shape
- Folded, zig-zag layers right next to the nucleus.
- Function
- Rough ER: makes and folds proteins. Smooth ER: makes lipids (fats). Both transport materials in vesicles.
Found in: Plant and animal cells
Nickname: a highway
Key words: Lipids = fats; Vesicle = a small membrane bubble that carries materials
About this video
A short animated close-up, under one minute, with three chapters: where the organelle is, its structure and shape, and its function. There is no sound; the words appear in the caption box. The card beside the video lists the same terms.
How to use it
The video shows rough ER with ribosomes as white dots. Ask: "Why is it called rough?"
Correction from the workbook chart
The workbook says the ER transports "mRNA and proteins." mRNA does not travel through the ER; it leaves the nucleus through the nuclear pores. Rough ER makes and folds proteins; smooth ER makes lipids.
Full script
Golgi body
Organelle 6 of 13- Structure
- Stack of flattened membrane sacs (cisternae) with vesicles at the edges.
- Shape
- A stack of pancakes or a WiFi symbol.
- Function
- Modifies, sorts, and packages proteins into vesicles and ships them.
Found in: Plant and animal cells
Nickname: the shipping department
Key words: Cisternae = the flat sacs of the stack; Vesicle = a small membrane bubble that carries materials
About this video
A short animated close-up, under one minute, with three chapters: where the organelle is, its structure and shape, and its function. There is no sound; the words appear in the caption box. The card beside the video lists the same terms.
How to use it
A post-office comparison works well: packages arrive, get sorted and labeled, and leave in trucks (vesicles).
Correction from the workbook chart
The workbook says protein is "stored" in the Golgi. The Golgi modifies, sorts, and packages proteins; it does not store them.
Full script
Quick Check 6
Follow the protein.
What this checks
The order rough ER, then Golgi body. Choice C catches students who mix up rough and smooth ER.
Mitochondria
Organelle 7 of 13- Structure
- Double membrane: smooth outer membrane + folded inner membrane (cristae). Inner fluid: matrix. Has its own DNA.
- Shape
- Oval, like a hot dog with zig-zag mustard.
- Function
- Cellular respiration: glucose + oxygen → energy (ATP) + carbon dioxide + water.
Found in: Plant and animal cells
Nickname: the powerhouse of the cell
Key words: Cristae = the folds of the inner membrane; Glucose = a sugar; ATP = the energy molecule cells use
About this video
A short animated close-up, under one minute, with three chapters: where the organelle is, its structure and shape, and its function. There is no sound; the words appear in the caption box. The card beside the video lists the same terms.
How to use it
Pause in chapter 3 and ask students to name what goes in (sugar, oxygen) and what comes out (energy the cell can use, carbon dioxide, water).
Correction from the workbook chart
The workbook says mitochondria "make the energy." Energy cannot be created; mitochondria release the energy stored in glucose.
Common mistake
Plant cells have mitochondria too, not only chloroplasts.
Full script
Lysosomes
Organelle 8 of 13- Structure
- Single-membrane sac filled with digestive enzymes.
- Shape
- Small, round sac.
- Function
- Breaks down worn-out organelles, food particles, and invading bacteria.
Found in: Mainly animal cells
Nickname: the clean-up crew
Key words: Enzyme = a protein that speeds up a reaction; digestive enzymes break things down
About this video
A short animated close-up, under one minute, with three chapters: where the organelle is, its structure and shape, and its function. There is no sound; the words appear in the caption box. The card beside the video lists the same terms.
How to use it
Ask: "Why does the lysosome need a membrane?" (To keep its enzymes away from the rest of the cell.)
Correction from the workbook chart
The workbook says the lysosome "patrols" the cell, captures invaders, and "spits them back outside," and marks it "Both." Lysosomes break down worn-out parts, food particles, and germs the cell has taken in, and much of the material is reused. They are mainly an animal-cell organelle.
Common mistake
Plant cells do this clean-up job mostly in their central vacuole, which is why lysosomes are described as mainly in animal cells.
Full script
Quick Check 7
Think about structure and function together.
What this checks
How a structure (folds) fits a function (more space to release energy). Choice D catches a mix-up with chloroplasts.
Vacuoles
Organelle 9 of 13- Structure
- Membrane sac filled with fluid: water, salts, sugars, wastes.
- Shape
- Small, round pouches (animal cells have a few).
- Function
- Storage of water, food, and wastes.
Found in: Plant and animal cells
Nickname: a sports-drink pouch
About this video
A short animated close-up, under one minute, with three chapters: where the organelle is, its structure and shape, and its function. There is no sound; the words appear in the caption box. The card beside the video lists the same terms.
How to use it
This spotlight covers the small vacuoles of animal cells. The giant central vacuole of plant cells has its own spotlight later.
Correction from the workbook chart
The workbook marks the vacuole "Animal." Vacuoles are found in both kinds of cells: small ones in animal cells, one giant central vacuole in plant cells.
Full script
Centrioles
Organelle 10 of 13- Structure
- A ring of 9 triplets of microtubules.
- Shape
- Short cylinders in pairs, at right angles; like rigatoni noodles.
- Function
- Organize the spindle fibers during cell division.
Found in: Animal cells (most plant cells do not have them)
Nickname: the cell-division helper
Key words: Microtubule = a tiny hollow protein tube; Spindle fibers = fibers that pull chromosomes apart
About this video
A short animated close-up, under one minute, with three chapters: where the organelle is, its structure and shape, and its function. There is no sound; the words appear in the caption box. The card beside the video lists the same terms.
How to use it
This connects directly to the mitosis video in Topic 2. The "9 groups of 3" pattern is an extra detail for curious students.
Common mistake
Students often think centrioles pull the chromosomes. They organize the spindle fibers; the fibers do the pulling.
Full script
Quick Check 8
Compare plant and animal cells.
What this checks
Which organelles are found only in animal cells. Choice A is a very common misconception.
How the parts work together
Follow one protein from instructions to shipping. Use the step buttons.
All the time: mitochondria release energy for every step, and lysosomes break down worn-out parts so their materials can be reused.
Why this slide
The workbook gives each organelle a separate job. This slide shows how the jobs connect, using the workbook's own comparisons (control center, highway, factory, shipping department, powerhouse).
Common mistake
Students often think the nucleus builds proteins. It stores the instructions; ribosomes build.
Quick Check 9
Think about the protein's path.
What this checks
The full order of the protein’s path, from the slide just before. Each wrong order puts one step too early.
Map: inside a plant cell
Tap a part to see its name. Parts that plant and animal cells share open the slides you already saw.
How to use this map
Use the button to highlight the three plant-only parts (cell wall, chloroplasts, central vacuole). Their slides come next. Shared parts open the slides from the animal-cell section.
Workbook corrections
The cell wall and central vacuole corrections are in the notes of their own slides.
Cell wall
Organelle 11 of 13- Structure
- Cellulose fibers (+ lignin in woody parts). Plasmodesmata connect neighboring cells.
- Shape
- Rigid, boxy layer outside the cell membrane.
- Function
- Support, protection, and shape; holds back the water pressure of the vacuole.
Found in: Plant cells
Nickname: a cardboard box
Key words: Cellulose = tough fibers plants make from glucose; Lignin = a hard material in wood; Plasmodesmata = tiny channels through the wall
About this video
A short animated close-up, under one minute, with three chapters: where the organelle is, its structure and shape, and its function. There is no sound; the words appear in the caption box. The card beside the video lists the same terms.
How to use it
Fungi and many bacteria also have cell walls, but made of different materials. The workbook only covers plant cell walls.
Correction from the workbook chart
The workbook says the cell wall "contains lignin." Every plant cell wall is mostly cellulose; lignin is added only in woody and stiff parts (wood, stems, veins).
Full script
Quick Check 10
Think about what makes plants stiff.
What this checks
What the cell wall is made of. Choice B is the workbook’s original claim, corrected.
Chloroplasts
Organelle 12 of 13- Structure
- Double membrane; stacks of thylakoids (grana) in a fluid (stroma). Contains chlorophyll.
- Shape
- Green oval with tiny beans (stacks) inside.
- Function
- Photosynthesis: light + water + carbon dioxide → glucose + oxygen.
Found in: Plant cells (and algae)
Nickname: a solar panel
Key words: Thylakoid = a disc-shaped sac; Granum (grana) = a stack of thylakoids; Stroma = the fluid around the stacks; Chlorophyll = green pigment that captures light
About this video
A short animated close-up, under one minute, with three chapters: where the organelle is, its structure and shape, and its function. There is no sound; the words appear in the caption box. The card beside the video lists the same terms.
How to use it
Pair chapter 3 with the mitochondria spotlight: the chloroplast makes the sugar, and the mitochondria release its energy.
Common mistake
Students often think plants get their food from the soil. The sugar is made in the chloroplasts from water and carbon dioxide; soil supplies water and minerals.
Full script
Central vacuole
Organelle 13 of 13- Structure
- One large sac with its own membrane (tonoplast), filled with cell sap: water, salts, sugars, pigments.
- Shape
- Takes up most of the plant cell.
- Function
- Stores water; creates turgor pressure against the cell wall so the plant stays firm.
Found in: Plant cells
Nickname: a water balloon
Key words: Tonoplast = the vacuole’s membrane; Turgor pressure = water pressure pushing on the cell wall
About this video
A short animated close-up, under one minute, with three chapters: where the organelle is, its structure and shape, and its function. There is no sound; the words appear in the caption box. The card beside the video lists the same terms.
How to use it
This is the idea behind the celery experiment later in the deck. Ask students to predict what happens to celery left in salty water.
Correction from the workbook chart
The workbook says the central vacuole is bigger "because plants can’t predict when they will get water next." Plants don’t predict. The real reason: the full vacuole presses on the cell wall (turgor pressure) and keeps the plant firm.
Full script
Sort it: plant, animal, or both?
This is the workbook's Venn diagram as a game. Choose where each part belongs. You'll see why right away.
The three planted mix-ups
- Mitochondria: many students say "plant only" or "animal only." Plants have both chloroplasts and mitochondria.
- Cell membrane: students think the wall replaces it in plants.
- Vacuole: the workbook marks it "Animal." It is in both.
Using the Venn diagram on paper
After the game, students can copy their answers into the workbook's Venn diagram (page 66).
Quick Check 11
Think about the plant cell.
What this checks
The corrected reason for the large central vacuole. Choice B is the workbook's original explanation, used here as a distractor with a clear reason why it is wrong.
Home experiment 2: crisp or limp celery?
Test what happens to plant cells when their central vacuoles gain or lose water.
Expected result
After about 24 hours: A is firm; B bends easily and feels rubbery; C is limp too. Adding a drop of food coloring to cup A also shows water moving up the stalk.
Vocabulary you may add
Water moving across a membrane is called osmosis. It is not required at this level, so it is only in this note.
Cells in everyday life
Chesapeake Bay
The Bay is full of phytoplankton: single-celled living things that float in the water. In spring, huge numbers of one kind can turn the water reddish-brown. People call this a "mahogany tide."
Bread and pizza dough
Dough rises because yeast cells use the sugar in it for energy and release gas bubbles. That's your experiment 1 in the kitchen.
Fall leaves in Northern Virginia
In fall, maple leaves stop making green chlorophyll. The chloroplasts' green fades, uncovering yellow and orange colors that were hiding there all along.
The grocery store
Stores mist lettuce and celery with water. This keeps the plant cells' central vacuoles full, so the vegetables stay crisp.
Energy can't be created or destroyed, only changed. That's why mitochondria release energy from food instead of making it.
Sources for the local examples
- Mahogany tides in the Chesapeake Bay are blooms of a single-celled alga (a dinoflagellate); reported by the Chesapeake Bay Program and Virginia agencies.
- Fall leaf color: chlorophyll breaks down, showing yellow and orange pigments already present.
Links
The "Next" link opens the Topic 2 file if both files are saved in the same folder.
Vocabulary flip cards
Say the meaning out loud, then tap the card to check.
Game idea
Pairs: one student reads the back, the other names the term.
Final quiz: Cell Theory
Answer all 8, then check your answers. Every answer comes with an explanation.
Answer key
1 C · 2 B · 3 D · 4 A · 5 B · 6 D · 7 C · 8 A
Note
The workbook's Day 1 question page was not included in the file I received, so these questions are new ones that cover the same content.