--- title: Being a scientist — fair tests, guesses and evidence — a lesson of Mova's school · trees and pragmatics description: «Being a scientist — fair tests, guesses and evidence», a lesson of the world course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: A scientist starts with a question, makes a careful guess called a prediction, and then tests it to see whether the wor --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/) [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/) / Being a scientist — fair tests, guesse… # Being a scientist — fair tests, guesses and evidence Lesson 91 of the world course of Mova's primary school: 16 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/91-being-a-scientist/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/0/) — A scientist starts with a question, makes a careful guess called a prediction, and then tests it to see whether the world agrees. - [1](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/1/) — In a fair test you change only one thing and keep everything else the same, so that if the result changes, you know which thing caused it. - [2](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/2/) — You measure the results, repeat the test several times and look at all the evidence, even the results you did not expect. - [3](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/3/) — Two things happening together does not prove that one causes the other: more ice creams and more sunburns both happen in summer, but ice cream does not cause sunburn — the sunshine causes both. - [4](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/4/) — Example: to find out whether plants grow better with plant food, you grow two groups of the same plants in the same pots, soil, light and water, and give plant food to only one group. - [5](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/5/) — A prediction is a guess about what will happen, based on what you already know. - [6](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/6/) — In a fair test only one thing is changed and everything else is kept the same. - [7](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/7/) — The thing you change on purpose is called the variable you are testing. - [8](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/8/) — A control group is kept without the change so you can compare the results with it. - [9](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/9/) — Repeating a test makes the result more trustworthy. - [10](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/10/) — Testing many plants or people is better than testing just one. - [11](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/11/) — Evidence is what you observe and measure, not what you hope or believe. - [12](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/12/) — A wrong prediction is still useful, because it teaches you something. - [13](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/13/) — Two things happening together does not prove that one causes the other. - [14](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/14/) — Scientists change their minds when good new evidence shows they were wrong. - [15](https://md.mova.elamur.ai/free/en/corpora/school/world/91-being-a-scientist/15/) — Scientists write down their method so that others can repeat the test and check it. - ← previous: [Measuring the world — length, mass, time and temperature](https://md.mova.elamur.ai/free/en/corpora/school/world/90-measuring-the-world/) - next →: [The human life cycle and growing up](https://md.mova.elamur.ai/free/en/corpora/school/world/92-human-life-cycle/) - ↑ back to [World](https://md.mova.elamur.ai/free/en/corpora/school/world/)