--- title: The air we breathe — a lesson of Mova's school · trees and pragmatics description: «The air we breathe», a lesson of the chemistry course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Wave your hand fast and you feel something push back: air. --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Chemistry](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/) / The air we breathe # The air we breathe Lesson 33 of the chemistry course of Mova's primary school: 19 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/chemistry/33-the-air-we-breathe/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/0/) — Wave your hand fast and you feel something push back: air. - [2](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/2/) — Push an "empty" glass upside down into a bowl of water and the water will not fill it, because the glass is full of air. - [3](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/3/) — Old diving bells kept people dry under water the same way. - [4](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/4/) — Air is mostly nitrogen, which hardly reacts, with about a fifth oxygen that we breathe, and tiny amounts of other gases such as carbon dioxide, which plants take in and which traps heat like a blanket. - [5](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/5/) — Air can get dirty with smoke and fumes, and people have changed it: we put holes in the ozone layer and are adding carbon dioxide. - [6](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/6/) — Yet when the world agreed to act, the ozone layer began to heal. - [7](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/7/) — Air is a mixture of gases; it takes up space and has weight, even though you cannot see it. - [8](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/8/) — About 78 parts in 100 of air are nitrogen, about 21 are oxygen, and about 1 is other gases; carbon dioxide is only a tiny part. - [9](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/9/) — Nitrogen hardly reacts, so crisp packets are filled with it to keep the crisps fresh. - [10](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/10/) — Air presses on us from all sides, and the air and liquids inside our bodies press back out, so we do not feel its weight. - [11](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/11/) — High on a mountain the air is thinner, so each breath holds less oxygen; climbers on the highest mountains often carry oxygen tanks. - [12](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/12/) — Smog is a dirty haze of smoke and car fumes that builds up in still air; cleaner cars and fuels have made many cities' air clearer. - [13](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/13/) — The ozone layer, high in the sky, blocks much of the Sun's harmful ultraviolet light; some old spray-can and fridge gases damaged it. - [14](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/14/) — Those gases were banned by a world agreement in 1987, and the ozone hole has been reported to be slowly healing. - [15](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/15/) — Burning coal, oil and gas adds carbon dioxide to the air; carbon dioxide traps heat like a blanket, so even a small rise warms the planet. - [16](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/16/) — Plants take in carbon dioxide and give out oxygen while they use sunlight to make sugar; tiny plants in the ocean are thought to make about half of the world's oxygen. - [17](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/17/) — A few houseplants do very little to clean the air of a room; opening a window does far more. - [18](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/18/) — Fridges and air conditioners use special gases that soak up heat when they evaporate and give it out when squeezed; old fridges are recycled carefully so these gases do not escape. - [19](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/33-the-air-we-breathe/19/) — Air is full of tiny specks of dust, pollen and skin flakes; you see them dancing in a sunbeam because they reflect light, and pollen makes people with hay fever sneeze. - ← previous: [Recycling: giving materials a second life](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/32-recycling-second-life/) - next →: [Water: the most amazing liquid](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/34-water-amazing-liquid/) - ↑ back to [Chemistry](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/)