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We control the controlled variables by keeping them constant.

# Controlled Variable

This Biology quiz is called 'Controlled Variable' and it has been written by teachers to help you if you are studying the subject at middle school. Playing educational quizzes is a fabulous way to learn if you are in the 6th, 7th or 8th grade - aged 11 to 14.

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In scientific investigations there are three types of variable - key independent variable (what you change), dependent variable (what you measure) and the controlled variables (factors you control to ensure they are the same throughout your experiment to make it fair). This middle school Biology quiz is all about the third type.

1.
A fair test is one where everything is the kept same except for the...
dependent variable
controlled variable
independent variable
any variable
Only the independent variable is changed although the dependent variable will also be changing. The controlled variables remain constant
2.
In an experiment investigating the effect of acid concentration, which of these is a controlled variable?
Volume
Size of beaker
Same beaker
Time of day
The container the acid is in and the time of day are nothing to do with the concentration of an acid
3.
If we fail to control variables, the results from the experiment may not be...
real
sufficient to draw a conclusion
accurately recorded
valid
The results will certainly be real but answers 2 and 3 depend on the person carrying out the experiment and not on controlled variables
4.
In an ecology experiment, we must always use quadrats of the same...
material
volume
mass
size
Studies involving quadrats require calculations made on area so using quadrats of different sizes would mean each sample would be taken over a different area. The control variable of area would therefore not have been controlled properly and could give invalid results
5.
What is a variable?
Any factor involved in the experiment
No factor of relevance
Only the controlled variable
The factor we change
At the start of an investigation, you should list as many variables as you can
6.
In an experiment on the effect of temperature on germination of cress seeds, which of the following would be controlled variables?
Temperature and size of seeds
Size of seeds and time
pH and temperature
Temperature and volume of water
Temperature is the independent variable in this experiment so it cannot be a controlled variable. Any answer to this question containing the word temperature must therefore be wrong
7.
Control variables are...
all of the factors
all the factors apart from the dependent and independent variables
none of the factors
the key independent variable
Control variables should be kept as constant as possible during your experiment
8.
We control the controlled variables by keeping them...
constant
different
larger
smaller
Controlled variables must be kept the same
9.
During a drug trial, which of the following are controlled variables?
Age and lifestyle
Gender and age
Gender and household income
Age and household income
Lifestyle could have an effect on the results but is very complex and includes many other variables. It is for that reason that it would not really be regarded as a variable but more as a group of variables
10.
Unless we keep the controlled variables the same, the investigation will not be...
correct
fair
right
wrong
A fair test is where the controlled variables are kept constant
Author:  Donna Maria Davidson