Science is the study of the world around us and scientists are people who look at the world and ask some very simple questions about it What is everything made of Why does everything move the way it does Why is everything arranged this way rather than any other way the scientific method In order to answer these questions scientists go out and investigate the world by performing experiments An experiment is a test we carry out on something in the world to see if it will behave the way we think it will For example we might like to find out where rainbows come from Perhaps you’ve noticed that rainbows only seem to appear when there is sunshine and rain in the sky at the same time So we might guess that some combination of sunshine and rain causes a rainbow In scientific terms this guess is called a hypothesis
To see if our hypothesis is right or not we can conduct an experiment Let’s try creating our own rain using a spray of water from a hosepipe first spraying the water on a sunny day where we expect to make a rainbow and then spraying the water on a cloudy day where we don’t expect to make a rainbow HOW ABOUT TRYING THIS EXPERIMENT YOURSELF WHAT DO YOU THINK WILL HAPPEN SUNNY DAY CLOUDY DAY When we do this experiment we are collecting scientific results If these results match our guesses then our hypothesis is correct If not we will have to go back to the drawing board and try to work out what else might be causing the rainbows This is what scientists do all the time They make a hypothesis about how the world works and then design an experiment to test it When a hypothesis proves to be true scientists explain why it is true using a theory
measurement An important part of any experiment involves measuring and there are many ways that physicists can measure an experiment and many different instruments they can use to get accurate results The standard measurement that scientists use to measure lengths and distances everywhere in the world is the metre which is about the width of a normal doorway 1000 mm 1 m 1000 m 1 km We use millimetres to measure very small things there are a thousand millimetres in one metre and kilometres to measure very large things there are a thousand metres in one kilometre To measure distance you can use a ruler or a metre stick 10 9 8 11 12 CATEX 1 7 6 5 2 3 4 TICK TOCK TICK TOCK The standard unit of time is the second There are 60 seconds in one minute and 60 minutes in one hour Clocks are a very important part of our everyday life because they show us when to get up and when to eat But we also use time to measure how long it takes for something to happen For example how long do you think it will take you to run from one side of the playground to the other You can measure how long this takes by using a stopwatch
Temperature is used to measure how hot or cold something is We use an instrument called the thermometer to measure temperature Scientists measure how much mass something has but this is not to be confused with measuring how much something weighs Weight is a measure of how heavy something is on the surface of the Earth when gravity is pulling it down For example an elephant has a large weight on Earth but it would weigh virtually nothing out in space because there is almost no gravity pulling it down Mass is a measure of how much stuff known as matter there is inside something and this stays the same wherever the thing is So the elephant would have the same mass in space as it does on Earth because it is still made out of the same stuff We measure temperature using units called Celsius or Fahrenheit Zero degrees Celsius is the temperature at which pure water freezes which is 32 degrees Fahrenheit 100 degrees Celsius is the temperature at which pure water boils which is 212 degrees Fahrenheit The standard unit of mass is the kilogram One kilogram is the mass of a bag of sugar Scientists use weighing scales to measure everyday masses but they have much more complicated techniques to measure the lightest and heaviest things in our Universe
