2Learning OutcomesWhat are variables?The difference between independent, dependent and controlled variables.Examples
3Variables When doing an investigation vary change Three types of variablesVery important
4Variables 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.
5Scientific experiments have three types of variables. Three kinds of variablesIndependentControlleddependent
6The 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.
7The 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."
8In 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).
9Put 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’andthe independent variable on the ‘horizontal axis’.
10Variables Dependent Independent controlled What I change What I keep the sameWhat I observe or what will be measured or affected
11What is a variable? What are the three types of variables? Test your knowledgeWhat 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…….
12Do fertilisers make a plant grow bigger? ExampleDo fertilisers make a plant grow bigger?Three kinds of variablesdependentIndependentControlled1- Same type soil2- Watered at the same time3- Same type plant4- Same amount of fertiliser5- Same amount of water6- kept in the same placeType of fertilisersThe growth of the plant
13Example Independent variable Dependent variable Does a fertiliser make a plant bigger2- 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.
14Answers Example Independent variable Dependent variable Does a fertiliser make a plant biggerType of fertiliserGrowth of plant2- Does heating a cup allow it to dissolve more sugar?Temperature of the waterAmount of sugar that dissolves completely3- Does an electric motor turn faster if you increase the voltage?Voltage of the electricitySpeed of rotation4- How much water flows through a pipe at different openings?Water pipe opening (closed, half open, fully open)Amount of water flowing5- Which types of ball bounces the highest after being dropped onto the ground?Type of ballsHeight of which the ball bounces6- Effect of temperature on the amount of sugar dissolved in tea.Temperature of waterAmount or mass of sugar dissolvedAnswers
15Test 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:
16Task:Complete the worksheets.Play the variables game.