--- title: Materials and their properties — a lesson of Mova's school · trees and pragmatics description: «Materials and their properties», a lesson of the world course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: We choose a material for a job because of its properties. --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/) [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/) / Materials and their properties # Materials and their properties Lesson 18 of the world course of Mova's primary school: 18 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/18-materials-and-properties/). - [1](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/1/) — We choose a material for a job because of its properties. - [2](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/2/) — Heat moves easily through some materials, called conductors of heat, such as metals; it moves slowly through insulators, such as wood, plastic, wool, cork and air trapped in tiny pockets. - [3](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/3/) — An object floats if it is less dense than the water: it has less mass than the same amount of water would have. - [4](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/4/) — A steel ship floats because its hollow shape is full of air and pushes aside a great deal of water. - [5](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/5/) — Some solids dissolve in water: sugar and salt break up into particles too small to see and spread through the water, making a solution. - [6](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/6/) — Sand and pepper do not dissolve. - [7](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/7/) — For example, a metal spoon left in hot tea soon has a hot handle, but a wooden spoon does not, because metal conducts heat and wood insulates. - [8](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/8/) — Metals are good conductors of heat and of electricity. - [9](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/9/) — Wood, plastic, wool, cork and still air are poor conductors of heat, called insulators. - [10](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/10/) — A warm coat does not make heat; it slows down the loss of your own body heat. - [11](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/11/) — Insulators also keep cold things cold, like food in a cool box. - [12](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/12/) — Double-glazed windows have two sheets, or panes, of glass with a layer of trapped air between them. - [13](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/13/) — An object floats if it is less dense than water, and sinks if it is denser. - [14](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/14/) — Whether an object floats depends on its material and its shape, not on its weight alone; things with air inside them, like an apple, are less dense and float more easily. - [15](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/15/) — A dissolved solid is still there: a solution weighs as much as the water and the solid together. - [16](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/16/) — Sugar dissolves faster in warm water and when it is stirred, and more of it can dissolve in hot water than in cold. - [17](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/17/) — Sand, pepper and cooking oil do not dissolve in water. - [18](https://md.mova.elamur.ai/free/en/corpora/school/world/18-materials-and-properties/18/) — Dissolving can be reversed: you can get salt back by letting the water evaporate. - ← previous: [Air and why we need it](https://md.mova.elamur.ai/free/en/corpora/school/world/17-air-oxygen-carbon-dioxide/) - next →: [Mixtures and how to separate them](https://md.mova.elamur.ai/free/en/corpora/school/world/19-mixtures-and-separating/) - ↑ back to [World](https://md.mova.elamur.ai/free/en/corpora/school/world/)