--- title: Birds: feathers, nests and flight — a lesson of Mova's school · trees and pragmatics description: «Birds: feathers, nests and flight», a lesson of the world course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Feathers are made of keratin, the same stuff as our hair and nails. --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/) [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/) / [World](https://md.mova.elamur.ai/free/en/corpora/school/world/) / Birds: feathers, nests and flight # Birds: feathers, nests and flight Lesson 73 of the world 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/world/73-birds-feathers-nests-flight/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/0/) — Feathers are made of keratin, the same stuff as our hair and nails. - [1](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/1/) — Long, stiff flight feathers on the wings and tail catch the air, and soft, fluffy down feathers close to the skin trap warm air like a duvet. - [3](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/3/) — A wing is curved, so as the bird moves forward the air flowing past pushes it upward; this push is called lift. - [4](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/4/) — Flapping pushes air down and back, so the bird is pushed up and forward. - [5](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/5/) — A bird's beak shows what it eats: a hooked beak tears meat, a short thick beak cracks seeds, a long thin beak reaches nectar in flowers and a flat beak sifts food from water. - [6](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/6/) — For example, a bird preens every day, combing its feathers with its beak and spreading oil from a gland near its tail, so a duck stays dry even after a dive. - [7](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/7/) — Feathers are made of keratin, the same material as hair and nails. - [8](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/8/) — Down feathers trap air and keep a bird warm. - [9](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/9/) — Many of a bird's bones are hollow, which makes it light for flying. - [10](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/10/) — A bird's strong flight muscles are fixed to a keel on its breastbone. - [11](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/11/) — The curved shape of a wing gives lift as air flows past it. - [12](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/12/) — Birds have no teeth; a muscly part of the stomach called the gizzard grinds their food, often with swallowed grit. - [13](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/13/) — Long narrow wings are good for gliding, like an albatross's, and broad wings are good for soaring on rising warm air, like an eagle's. - [14](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/14/) — A hummingbird can hover by beating its wings dozens of times a second. - [15](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/15/) — Birds preen to keep their feathers clean, tidy and waterproof. - [16](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/16/) — Birds keep their eggs warm with their own bodies until the chicks hatch. - [17](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/17/) — Birds build many kinds of nests: cups of twigs, woven baskets, mud nests and holes in trees. - [18](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/18/) — A cuckoo lays its eggs in other birds' nests and lets them raise its chicks. - [19](https://md.mova.elamur.ai/free/en/corpora/school/world/73-birds-feathers-nests-flight/19/) — Birds are living descendants of dinosaurs. - ← previous: [Insects and spiders](https://md.mova.elamur.ai/free/en/corpora/school/world/72-insects-and-spiders/) - next →: [Fish, frogs and reptiles](https://md.mova.elamur.ai/free/en/corpora/school/world/74-fish-frogs-reptiles/) - ↑ back to [World](https://md.mova.elamur.ai/free/en/corpora/school/world/)