Experimental design

• Independent Variable (IV)


  What you are choosing to change or test when you conduct your experiment
• Dependent Variable (DV)


  What you are going to measure or observe in your experiment
• Controlled Variable/s


  Things that you need to keep the same (constant) to ensure that your result is fair
• Need to justify why it is important to control these variables
• Research Question / Scientific Question


  A question that clearly describes the purpose of the investigation, including the IV and DV
• Aim


  A sentence about what you are going to be testing, including the IV and DV
• Hypothesis


  An educated guess / prediction of how the IV will affect the DV
• A controlled experiment MUST have at least 2 groups
• Experimental Group


  Group on which the condition that you are testing (independent variable) is changed
• Control Group


  Group on which all conditions remain the same, the IV is not applied or not changed
• All variables must be controlled the same as the experimental group in the control group
• Only 1 condition is changed in a controlled experiment
• Methods


  A numbered step-by-step guide saying how to do the experiment
• Methods should be easy to follow, use scientific language, and be short and simple
• Experiments are usually repeated multiple times for reliable results
• Methodology should be a summary of experimental method used with enough detail to allow others to repeat the experiment and get similar results
• Methodology is written in past tense and assumes the reader is a scientist
• Data tables need a descriptive title that includes the IV and DV, column headings with units, the IV in the left column, and the DV in the right columns