Lesson 2 – Variables
https://www.youtube.com/watch?v=iaewZmc4TYQ
https://www.bbc.co.uk/bitesize/guides/zcxp6yc/revision/1
There are three kinds of variable, dependent, independent and control.
Scientists often want to find out if changing one variable makes a difference to
other variables.
Control variables are factors that are kept constant throughout the
investigation.
Independent variable: A factor that is changed on purpose to see if the
change has an effect on the dependent variable.
Dependent variable: A factor that is measured.
An example would be investigating whether increasing the temperature of the
reactants might alter the rate of the reaction.
As it is the temperature which is changing, that would be the independent
variable.
The changing temperature alters the rate of reaction, therefore the
reaction rate is the dependent variable.
When carrying out the experiment, care has to be taken that other
variables that affect the rate of reaction, such as concentration of
reactants, are kept constant. These are control variables.
Task: Identify the variables in the following situations.
Experiment
Independent
Variable
Dependent
Variable
Control
variable
Do earthworms
prefer wet or dry
soil?
Do bananas go
brown more
quickly if you
keep them in the
light or the dark?
