We breathe in when the diaphragm tightens and moves down: the chest gets bigger and air is pushed in, down the windpipe to the air sacs. When it relaxes, the air goes back out. Put this respiratory system simulation on the board and the class can watch a pair of 3D lungs do it. The diaphragm pulls down, the lungs stretch, and air runs down the windpipe and the branching tubes. Then it turns round and goes back out.
Watch it breathe: on the whole journey the diaphragm moves, the lungs stretch and the air runs in and out. Step through it: one sentence per step, with that part lit up and named on the model. Slow it down to follow the air. Hide the labels and ask the class to name the parts. Turn the model by dragging. Share copies a link that opens it at the step you are on.
Air goes through the nose and mouth, down the windpipe (trachea), into two bronchi, along smaller and smaller bronchioles and into the air sacs (alveoli). The diaphragm sits underneath. The board uses the everyday name where there is one, Windpipe and Air sacs, and gives the science name when you press it. Switch to More detail and the names become Trachea and Alveoli, with the cartilage rings and the capillaries round the alveoli added, and the explanations cover cilia, diffusion and the intercostal muscles. For a label the lungs quiz, press Labels once and each name hides behind a question mark. Print gives a pupil sheet with blank label lines and a word bank.
No. Lungs are soft and spongy, not muscle, and cannot move themselves. The diaphragm, a dome of muscle underneath, makes the chest bigger and smaller, and the lungs follow. The ribs help too: they move up and out as you breathe in. Lungs do not suck air in. The chest gets bigger, and the air outside is pushed in. On the whole journey you can watch the diaphragm flatten and the lungs stretch, then spring back.
No. Breathing moves air in and out of the lungs. Respiration is the chemical reaction inside every cell that uses oxygen to release energy from food. The two meet at the air sacs, where oxygen passes into the blood and carbon dioxide, the waste from respiration, passes out to be breathed away. The names do not help: the respiratory system is the breathing system. This simulation shows breathing.
In the bottle and balloon lung model, the bottle is the chest, the balloons are the lungs, the tube is the windpipe and the rubber sheet is the diaphragm. Pull the sheet down and the balloons fill, just as the lungs do on the board. The bell jar version works the same way. What both leave out is worth asking the class. The sides of a bottle cannot move the way ribs do, a balloon is one empty bag where a lung is millions of air sacs, and no oxygen passes into any blood.
The words are pitched at ages 9 to 14: Years 5 to 9 in England, 4th to 8th grade in the United States. In England breathing is Key Stage 3 biology: "the structure and functions of the gas exchange system in humans" and "the mechanism of breathing to move air in and out of the lungs". In the United States it supports NGSS 4-LS1-1, where the lung is one of the structures named, and MS-LS1-3, which covers the respiratory system.
What does the respiratory system simulation show?
The windpipe, the two bronchi and both lungs, cut open so the class can see inside. Air moves down the windpipe, into smaller and smaller tubes and on to the air sacs, where oxygen passes into the blood. The diaphragm pulls down on a breath in and relaxes on a breath out, and the air turns round with it.
What does the diaphragm do?
It pulls down to breathe in, so the lungs stretch and air rushes in. To breathe out it relaxes back up, the lungs get smaller and the air, now with more carbon dioxide, is pushed out.
What happens in the air sacs?
The tiniest tubes end in air sacs. Oxygen passes from the air into the blood the heart sends there, and waste carbon dioxide comes out of the blood to be breathed out.
Why is the left lung smaller?
To make room for the heart, which sits between the lungs and a little to the left. The right lung has three lobes and the left has two.
Why is the right lung on the left of the screen?
Because the lungs are drawn as if the person is facing you. Their right is on your left, and the label says so.
What has been simplified?
One thing, on purpose. Each real lung has both the branching tubes and the air sacs. The model shows the fine branching tubes in one lung and the air sacs in the other, so the class can see both clearly.
What age is it for?
Ages 9 to 14: upper Key Stage 2 and Key Stage 3 in England, 4th to 8th grade in the United States.
Is it free?
Free to try. Opening Science Simulations uses one token for the whole day, however many times you come back to it. Every account gets 20 free tokens, and Pro gives 50 a day.
The heart simulation follows the blood after it collects its oxygen. Plants swap gases too, through tiny holes in their leaves, which the transport in plants model names. All twelve are on the Science Simulations page. For models the class can spin, try 3D Explorer.