1. © SSER Ltd. How Science Works Types of Variable Slide 1

2. A variable is an observation, measurement, score, outcome or category which can take different values, such as: Data is any information, facts or figures collected as part of an experiment. Data is the result of measuring, counting or observing variables. Colours of CarsHeights of TreesScores from Dice Variables & Data Slide 2

3. Types of Variable There are many different types of variable. In an experiment, variables can be:  Continuous  Ordered  Independent  Categoric  Control  Discrete These variables can be further described as:  Dependent Slide 3 1 2 3 4 5 6 7

4. The independent variable is the variable you change in your experiment, so that you can measure the effect on the dependent variable. The Independent Variable The independent variable is also referred to as the input variable. The dependent variable is what you measure. The value of the dependent variable depends on the value of the independent variable. It is also often referred to as the output variable. Slide 4

5. Dependent & Independent Variables - Example 1 When investigating how temperature affects the germination of seeds, temperature is the independent variable and the number of seeds germinated is the dependent variable. Independent variable Controlled by temperature Dependent variable The temperature is controlled in the experiment and the germination of the seeds is affected by the temperature. Slide 5

6. When investigating the effect of volume on solubility, volume is the independent variable and the time taken for the solid to dissolve is the dependent variable. Dependent & Independent Variables - Example 2 Independent variable Controlled by volume Dependent variable The volume is controlled in the experiment and the time to dissolve is affected by the volume of solvent.

7. When comparing how the thickness of a material affects the insulation of 200cm 3 of water (coloured) at 60ºC, thickness of the material is the independent variable and the temperature of the water or the time taken to reach a certain temperature are dependent variables. Dependent & Independent Variables - Example 3 Thickness is the independent variable can be dependent variables Temperature or time

8. Identifying the Independent Variable For each of the following experiments, identify the independent variable…

9. Dependent or Independent? For each of these investigations, drag a variable label to the correct place in the sentence...