Model building means making a physical copy of something, using materials we can find, so we can study it more closely or show it to other people.
Project work
Before looking at models, here is one more kind of practical work: project work. A project usually means visiting a real place, studying it, and then writing a report with ideas for making it better. For example, a class might visit a nearby temple or cultural site, look at how clean and green the area is, and then write a report suggesting ways to improve it.
Why we build models
Some things simply cannot be looked at directly. Nobody can stand outside the solar system and see all the planets at once. Nobody can watch their own lungs working from inside their chest. An eclipse happens rarely, and when it does, you cannot pause it or turn it around to see it from another angle. In every one of these cases a model solves the problem, by making a small, safe, patient copy of something that is otherwise too big, too hidden, too fast, or too rare to study.
What is a collage?
A collage is a model made by collecting small objects or pieces and sticking them onto a surface. Using paper or other things found nearby, a collage can show something like an atom, a food chain, or how plants make their own food. It is the simplest kind of model to build, because it needs almost nothing beyond paper, glue, and a clear idea of what you are trying to show.
The globe and the solar system
A globe is a model of the Earth. Looking at a globe, we can see that the Earth is round and tilted slightly, the way a real globe usually stands. Photos of the sun and planets, or drawings of them, can also be collected and arranged to make a collage of the whole solar system.
★Sample Model Report: Human Lungs
- Objective
- To build a model that shows how humans breathe.
- Materials
- Two small balloons, one large balloon, scissors, a large plastic bottle, a tube, tape, glue, a Y-shaped connector.
Procedure: A tube was fixed tightly to the Y-shaped connector. A small balloon was tied to each of its two open ends. The bottom of the bottle was cut off. A hole was made in the cap, the tube was passed through it, and the join was sealed. The large balloon was stretched and tied over the cut opening at the bottom of the bottle.
Observation: Pulling gently on the knot of the large balloon made both small balloons inside the bottle grow bigger. Letting go made them return to their normal size.
Conclusion: Humans breathe as the lungs get bigger and smaller. The muscle that makes this happen is called the diaphragm.
What each part of the lung model stands for
A model is only useful once you know which real thing each of its parts is standing in for. Read this table, then look at Figure 1.10 again and point to each part on the picture.
| Part of the model | What it stands for in the body |
|---|---|
| Two small balloons | The two lungs |
| Tube and Y-shaped connector | The windpipe, splitting into two branches |
| The plastic bottle | The chest cavity that holds the lungs |
| The large stretched balloon | The diaphragm, the muscle below the lungs |
Here is what actually happens when you pull the large balloon down. Pulling it makes the space inside the bottle bigger. The air already inside now has more room, so it spreads out and pushes less hard. Air from outside, which is still pushing at its normal strength, is therefore stronger, and it flows down the tube into the two small balloons, filling them. Let go, the space shrinks again, and the air is pushed back out. Your own breathing works the same way. Your diaphragm pulls down, your chest space grows, and air flows in on its own. You do not suck air in so much as make room for it.
Every model is a simplified copy
This is the most important idea in the whole topic, and it is one that many students miss. A model is never the real thing. It is always simpler, and the person who built it chose what to leave out. A good scientist knows both what a model shows and what it quietly ignores.
The lung model
Shows how the diaphragm changes the chest space. But real lungs are soft and spongy, not smooth like balloons, and the model has no ribs at all.
The globe
Shows the shape of the Earth and its tilt correctly. But it does not spin on its own, and the mountains on it are far too large compared to the real Earth.
The solar system model
Shows the order of the planets and their rough sizes. But the distances are hopelessly wrong, because a model with correct distances would not fit inside any classroom.
So is a model wrong?
No. A model is built to answer one question well. It is only wrong if you ask it a question it was never built to answer, such as asking a classroom solar system how far Mars really is.
Look around your home for things you could turn into a model. Bottle caps, cotton, dry leaves, or old boxes can all become parts of a science model. The best models are usually made from whatever was already lying around, not from anything bought.
A model is only useful if it is labelled clearly. A beautiful model with no labels does not tell the viewer which part is which, so it fails at its main job. If someone has to stand beside your model and explain it out loud, the model is not finished. The labels should do that work for you.
TODO: Add YouTube video ID for Model Building
Build a Simple Collage
Here is how one student completed this activity, choosing the water cycle. Notice that she wrote down what her model shows well and what it leaves out, which is the part most students forget.
★My Collage: The Water Cycle
- Idea chosen
- The water cycle, because I wanted to show something that keeps going round instead of stopping.
- Materials I used
- Blue paper for the sea, cotton wool for the clouds, silver foil from a chocolate wrapper for the rain, brown paper for the hill, and a green leaf for the tree.
What I built: I glued the blue paper along the bottom for the sea, and put the brown hill on the right. Above the sea I stuck two cotton wool clouds. I cut thin strips of silver foil and glued them slanting down from the cloud onto the hill, for rain. Then I drew arrows in red pencil going all the way round: up from the sea, across to the hill, down as rain, and back along the ground to the sea again.
Labels I added: evaporation on the arrow going up from the sea, condensation on the clouds, precipitation on the foil rain, and collection on the arrow running back to the sea. I also labelled the sun in the corner, because without it nothing would evaporate at all.
What my model shows well: It shows the order of the four stages clearly, and the red arrows make it obvious that the water goes round and round rather than being used up.
What it leaves out: My cotton clouds sit still, but real clouds are blown along by wind, sometimes for hundreds of kilometres, so rain often falls far from where the water evaporated. My model makes it look like the rain lands right next to the sea it came from, which is not always true.
I showed my collage to Sabin without saying a word about it, the way our teacher asked. He got evaporation and rain straight away from the labels, but he thought the red arrows were lightning, not the path of the water. So I went back and made the arrows thinner and added the word cycle in the middle of the loop. That fixed it for the next person I showed. The thing I did not expect is that writing down what my model leaves out was the part I learned most from. Until I had to write that sentence about the wind, I had not really thought about where rain actually comes from.
| Question | My answer |
|---|---|
| Which science idea did I choose? | - |
| What did I use to build it? | - |
| Which parts did I label? | - |
| What does my model show well? | - |
| What does my model leave out? | - |
Model building means making a physical copy of something to study or show it.
Project work means visiting a real place, studying it, and writing a report with ideas to improve it.
A collage is a model made by sticking small pieces onto a surface.
Models let us study things that are too big, too hidden, too fast, or too rare to see directly.
A globe is a model of the Earth, showing that it is round and slightly tilted.
In the lung model, the small balloons are the lungs and the large stretched balloon is the diaphragm.
Pulling the diaphragm down makes the chest space bigger, and air flows in on its own.
Every model is a simplified copy. The builder always chooses what to leave out.
A model is only wrong if you ask it a question it was never built to answer.
A model must be labelled clearly, or it fails to explain anything on its own.
Topic: Model Building · Science
Model Building
Science & Technology · Grade 7
The Simplest Model: A Collage
- Small pieces collected and stuck onto a surface
- Needs almost nothing: paper, glue, and a clear idea
- Can show an atom, a food chain, or how a plant feeds itself
The Globe and the Solar System
- A globe shows the Earth is round, and slightly tilted
- Painted balls and stones become a whole solar system
- Both let you walk around and point at something you could never visit