Variables Session 1

Learning Outcomes What are variables? The difference between independent, dependent and controlled variables. Examples

Variables When doing an investigation vary change Three types of variables Very important

Variables are an important part of science projects and experiments. What is a variable? A variable is any factor that can be controlled or changed in an experiment.

Scientific experiments have three types of variables. Three kinds of variables Independent Controlled dependent

The independent variable is the factor or condition that is intentionally changed (made different) by an investigator in an experiment. The dependent Variable is the variable that you measure or observe. The dependent variable gets its name because it is the factor that is dependent on the state of the independent variable. Independent and dependent variables are related to one another. A variable that is not changed is called a controlled variable.

The Independent variable is what the experimenter changes in order to do the experiment. (What I change). The dependent variable is what changes when the independent variable changes - the dependent variable depends on the outcome of the independent variable. (What I observe or measure). Controlled variables are quantities that a scientist wants to remain constant, and he must observe them as carefully as the dependent variables. Some people refer to controlled variables as "constant variables."

In summary: Independent Variables are changes that occur in an experiment that are directly caused by the experimenter (you.) Dependent Variables are changes that occur due to independent variables. A Controlled Variable is anything else that could influence the dependent variable. (Things that are kept the same).

Put the dependent variable on the ‘vertical axis’ The independent variable is usually graphed on the horizontal axis and the dependent variable on the vertical axis. Put the dependent variable on the ‘vertical axis’ and the independent variable on the ‘horizontal axis’.

Variables Dependent Independent controlled What I change What I keep the same What I observe or what will be measured or affected

What is a variable? What are the three types of variables? Test your knowledge What is a variable? What are the three types of variables? Which two variables are related? Complete the following: The independent variable is……. The dependent variable is…… Controlled variables are…….

Do fertilisers make a plant grow bigger? Example Do fertilisers make a plant grow bigger? Three kinds of variables dependent Independent Controlled 1- Same type soil 2- Watered at the same time 3- Same type plant 4- Same amount of fertiliser 5- Same amount of water 6- kept in the same place Type of fertilisers The growth of the plant

Example Independent variable Dependent variable Does a fertiliser make a plant bigger 2- Does heating a cup allow it to dissolve more sugar? 3- Does an electric motor turn faster if you increase the voltage? 4- How much water flows through a pipe at different openings? 5- Which types of ball bounces the highest after being dropped onto the ground? 6- Effect of temperature on the amount of sugar dissolved in tea.

Answers Example Independent variable Dependent variable Does a fertiliser make a plant bigger Type of fertiliser Growth of plant 2- Does heating a cup allow it to dissolve more sugar? Temperature of the water Amount of sugar that dissolves completely 3- Does an electric motor turn faster if you increase the voltage? Voltage of the electricity Speed of rotation 4- How much water flows through a pipe at different openings? Water pipe opening (closed, half open, fully open) Amount of water flowing 5- Which types of ball bounces the highest after being dropped onto the ground? Type of balls Height of which the ball bounces 6- Effect of temperature on the amount of sugar dissolved in tea. Temperature of water Amount or mass of sugar dissolved Answers

Test your knowledge The dependent variable: The independent variable: For the investigation “Which types of ball bounces the highest after being dropped onto the ground?”, state: The dependent variable: The independent variable: Controlled variables:

Task: Complete the worksheets. Play the variables game.

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By Zani Alam