Seeing Inside Cells

Initiate a class discussion prior to beginning the activity.

Paraphrase:

When we are trying to teach someone a new complex idea or concept, it is helpful to compare it to something similar.

One way of making a model is to make an analogy to something else that is easier to understand. Analogies can be very helpful in science. They use something we're familiar with to help us understand something we're less familiar with.

Show slide #1. Paraphrase:

How are a beehive and an apartment building similar?

But, of course no analogy is perfect. What are important differences between the two?

Clarify that analogies do not simply express how similar two things look physically, but also how similar they are in function. For example, the beehive “rooms” are like the rooms in the apartment building. The walls have similar functions keeping each “room” in the hive separate from the rooms in an apartment.

Show slide #2. Paraphrase:

How are a bird and an airplane similar?

But, of course no analogy is perfect. What are important differences between the two?

Show slide #3. Paraphrase:

How are a computer’s hard drive and a human brain similar?

But, of course no analogy is perfect. What are important differences between the two?

Analogies

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Before starting, review what the students know about cells. Paraphrase:

One way of making a model is to make an analogy to something else that is easier to understand. Analogies can be very helpful in science. They use something we're familiar with to help us understand something we're less familiar with.

Later, we'll make analogies about cells. What should we include in our analogy? Let's try to remember together some of the things that make cells cells. What do they do? What do they have inside and around them?

This activity will later ask the students to consider these functions and features of cells in their analogy, so help your students recall these aspects of the cell at a minimum. If the students generate other accurate details of cell structure and function, include those in your notes on the whiteboard or projection screen.

Cell structure and function: details to include in the analogies (suggested list)

• operating instructions
• getting energy
• obtaining building materials
• waste disposal
• when it gets too large, it splits into two
• cytoplasm
• nucleus
• mitochondria
• cell membrane
• organelle
• chloroplast (if your cell is like a plant cell)
• cell wall (if your cell is like a plant cell)

A School as a Cell

The school rules provide the school-cell's operating instructions.

Students, the district budget, and the PTA provide money which is like energy for the school-cell.

The front office orders paper, electronics, textbooks, cafeteria food, and all the materials the school needs to do its work: educating students. New kindergarteners are also new "materials."

We recycle, compost, and throw away trash to get rid of wastes. Graduating students are also waste, in a way.

When too many students are in the school, a new school with many of the same parts and pieces might be started nearby. Some of the students and teachers go to one school, and some stay at the original.

The cytoplasm of the school-cell is the campus.

The nucleus is the principal's office. In a school, the principal is responsible for everything that goes on in the school. He or she is the boss, very familiar with all the school rules, just like the nucleus controls what goes on inside the cell using the DNA as instructions. The nucleus is the "boss" of the cell.

The mitochondria is the copier machine that makes all the worksheets and tests for students to learn.

The cell membrane is the chain-link fence that keeps all the students inside. Security guards or school staff make sure that nobody gets on campus that's not supposed to be there.

Other organelles can be the different parts of the school-cell, like the library, cafeteria, classrooms, maintenance closet, locker room, etc.

Paraphrase:

A school is something we're all very familiar with. But you can also go in a different direction: more imaginatively.

Here's another example of the beginning of a more unusual analogy. When looking at cell models made of paper clips or pixels on a screen, cells seem very flat. In real life, cells are three-dimensional. An analogy that would work in three dimensions is an imaginary, interplanetary floating amusement park that you might imagine in a science fiction movie. We'll call it "Cytoworld." A story about it might begin like this.

Show the slide and read the first paragraph of the example narrative.

A cell is like a ...

Inside its force field, it’s like nothing you ever imagined, where dreams are transformed into screams of delight. Lucky kids from all over the universe want to go, but you can only get in with a ticket which the guards carefully check before bringing you in. The guards are very careful about who enters Cytoworld because there have been attacks in the park that nearly started an intergalactic war. These guards also hold the line because attendance is always at capacity, and they don’t want the lines inside to get too long. But the lines at the entrances are also growing very long, and you can see that some of the rides inside the park are running with nearly empty coaster cars. As you wait outside the boundary of the park with your friend Qeeqee, the two of you decide you will petition Chairman Cyto, the head of Cyto Industries, to build another Cytoworld to accommodate its popularity.…

Choose a thing

• City
• Country
• Construction Site
• Lab
• Kitchen
• House
• Restaurant
• Factory
• School
• Hospital
• Castle
• Mall
• Prison
• Human Body
• Sports Team
• … or your own idea!

Cell Part or Function / Similar Thing in Analogy / Explanation

operating instructions

getting energy

obtaining building materials

waste disposal

cytoplasm

nucleus

mitochondria

cell membrane

organelle

chloroplast (if your cell is like a plant cell)

cell wall (if your cell is like a plant cell)

Cell Analogy Project Requirements

1. Write clearly.
2. Explain main parts of the cell (the organelles).
3. Connect parts of the analogy to parts of the cell (the organelles).
4. Make the cell functions accurate.
5. Explain the analogy of the cell to a system.
6. Include your name, date, and the title of the analogy project.

Responding to the analogies

Use these sentence starters to give feedback to your classmates.

• I think other people might not notice that …
• Your project is unique because …
• Looking at it from a different perspective, I realized that …
• At first, I saw … but now, I see ….
• After studying this part carefully, I noticed that …
• This reminds me of …
• Which part is most important to you?
• What would happen if you made a change here?
• Is there a way to improve this by taking something away? Or adding to it?
• Does this make sense to you? Which parts are confusing?

• Analogy of the cell to a system is explained
• Writing/visual project represents analogy of the cell to a system
• Cell organelles are verbally explained in the analogy
• Components of analogy represent cell organelles
• Accuracy of cell functions
• Clarity of writing
• Title, name, date, and other required info is included on project
• Project presented clearly to the class
• After the critique, at least 2–3 pieces of constructive, peer feedback incorporated