(IES) Designing an Experiment - Design and Procedures Lesson

Designing an Experiment - Design and Procedures Lesson  

This is where we develop and plan our scientific investigation and actually DO the experimenting.

You can ask yourself four questions to help you decide how you will test your hypothesis.

Question 1 – What materials are readily available for conducting experiments on general topics of interest?

Question 2 – What action is observed when studying general topics of interest?

Question 3 – What are all the ways that I can change the set of materials that would change the action?

Question 4 — In what ways can I measure or describe the response to the change?

You can plan experiments by using the Experimental Design Diagram (EDD).

To complete an EDD you must determine the independent variable, the number of trials, dependent variable, constants, and how you are going to "level" your variables. 

Experimental Design Diagram

This is used as a way to put your ideas for an investigation on paper and begin to plan out your experiment.

  1. Title for experiment written as "the effect of the independent variable on the dependent variable"
  2. Hypothesis in the form of an "if-then" statement
  3. Independent variable
  4. Different levels of the independent variable
  5. Level of the independent variable that will serve as the control for the experiment
  6. Number of repeated trials for each level of the independent variable
  7. Dependent variables, including how they will be measured
  8. Constants

Not ALL scientific investigations require a formal written plan like an EDD

Click here to view a blank template of the Experimental Design Diagram. Links to an external site.

See the following example of a completed EDD below.

Example:

  1. Title The Effect of Different Salt Concentrations on Bean Plant Growth
  2. Hypothesis if the salinity of the solutions is increased, then the plant growth will be decreased.
  3. Independant Variable - Salt Solutions
The Effect of Different Salt Concentrations on Bean Plant Growth
  1. 4) 0% salt concentration
  2. 5) (Control)
 10% salt concentration 20% salt concentration 30% salt concentration
6) # of trials - 25 plants 25 plants 25 plants 25 plants
  1. Dependent Variable Plant Growth (cm)
  2. Constants (CV) amount of light

                      amount of water

                      type of soil & fertilizer

                      type of plant, etc.

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