The student is going to try raising plants.
He wants to raise mint plants so he can make nice calming mint tea.
He buys 3 plants, but he is unsure how much water they need.

Design an experiment to test how much water they need.

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​Experimental Scenario

Experimental design

independent variable: The variable that is being tested. It is changed ON PURPOSE.

dependent variable: The "readout" of the experiment - the result that is measured and reported.

controlled variables: variables that MUST BE HELD CONSTANT throughout the experiment to make the test valid.

Remember the yeast respiration lab:

control conditions:

1 tsp yeast
1 tsp glucose
20 mL water
40 C

TEST conditions:


each group tested one condition. What did you test?

Remember the yeast respiration lab:

control conditions:

1 tsp yeast
1 tsp glucose
20 mL water
40 C

TEST conditions:


each group tested one condition. What did you test?

for example: Some people tested sucrose. .

So INDEPENDENT variable was sugar source.
DEPENDENT variable was size of balloon.

Other variables had to be controlled: amount of water, temperature, amount of yeast amount of sugar.

Analyze a graph

When graphing, the independent variable is always on the x-axis.

The dependent variableis always plotted on the y-axis.

What were the independent variables in this experiment?
Dependent variable?

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Analyze a graph

time is the independent variable whenever something is monitored over a period of time.



What is being monitored in this graph? (check the title and y-axis)

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In the mint plant scenario - -


Which variable would go on the x-axis?


What could you put on the y-axis?

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​Experimental Scenario

Which amount sof water are working?
Which is too much? which is too little?

Is the plant very picky about how much water it gets?

How much is too much water?

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