Designing a Controlled Experiment

Observation: People use fertilizer on plants Question: Does fertilizer cause plants to grow faster? Hypothesis: I think fertilizer will cause plants to grow faster because…

Creating Groups To do a controlled experiment make two groups that are the same but only test one Control group Not tested so you can compare to experimental group **Demonstrates the normal standard Experimental group Directly tested Include the more groups the better idea

Multiple Samples Five or more samples for each group returns better results Experimental group x5 Control group x5 Include the more groups the better idea

Identifying Your Variables Constant Variables are all of the things you keep the same for the two groups. Name the controlled variables: Include the more groups the better idea 5

Identifying Your Variables The Manipulated variable is what you change on purpose in your experiment. Its what you are testing. Ask yourself, what is different between the groups? ***Look for the one thing you do to the experimental group that you do not do to the control group Include the more groups the better idea What is the manipulated variable in this experiment? The fertilizer 6

Identifying Your Variables Responding variable is what you are looking for to change as a result of the manipulated variable It could be something you observe or measure Include the more groups the better idea What would be the responding? The height/growth of the plants 7

What are the 4 essential parts of a controlled experiment? Control Group Experimental Group Manipulated Variable Responding Variable Include the more groups the better idea 8