Experimental Variables Different factors that can change during an experiment are known as variables .
Transcript
Slide 1
Experimental Variables Different factors that can change during
an experiment are known as variables.
Slide 2
1. Independent Variable Is the variable an experimenter can
change. Is Plant Growth Affected by: Examples: Sunlight Food Water
Temperature Change only 1 variable at a time
Slide 3
2. Dependent Variable Is the variable that occurs as a result
of the experimenters change. Examples: Size of the leaves Tallness
(cm of growth) Color of leaves Number of flower buds
Slide 4
Independent or Dependent? 1. You want to see if playing music
makes plants grow taller. What is the dependent variable in this
experiment? Plant Height
Slide 5
Independent or Dependent? You want to measure the effect of
different amounts of oxygen on the rate of yeast growth. What is
the dependent variable? Yeast Growth
Slide 6
Independent or Dependent? An entomologist (bug scientist) wants
to determine if temperature changes how many times a cricket
chirps. What is the independent variable? Temperature
Slide 7
Independent or Dependent? You think that a certain part of your
brain is important in memory. To test this, you will remove this
part of the brain from rats and see if they remember how to get
through the maze. What is the independent variable in this
experiment? Removal of a certain part of the brain
Slide 8
When Designing an Experiment keep these in mind! You change
only 1 variable at a time when experimenting. The rest of the
variables you would hold CONSTANT.
Slide 9
1. Control Group Contains all the parts of an experiment EXCEPT
the one experimental factor being tested. A control is a standard
to which you can compare your results.
Slide 10
2. Experimental Group Contains all the factors of the control
group PLUS the one factor that is being tested.
Slide 11
Harvester ants often strip a bush of all of its leaves. Some
people believe this helps the plant grow thicker, healthier stems.
In an experiment, a student stripped off all the leaves from a set
of plants. In a second set of identical plants, the student allowed
ants to strip off the plants leaves. In order to improve this
experimental design, it is most important to add a set of plants
that: HAVE LEAVES Control & Experimental Group
Slide 12
Experimental Controls When conducting an experiment, these are
the items that NEVER change What examples can we use from our
Inquiry Lab? Room temperature Rate of gravity Person dropping the
ball Thickness of sand layer What else???