Controlled Experiments Vocabulary and examples

What is a controlled experiment? A controlled experiment is a scientific test that takes place under controlled conditions. Controlled conditions (controlled variables) are things that must remain the same/ unchanged in an experiment in order for the results to be accurate.

How do we start a controlled experiment? A controlled experiment starts just like any other experiment: with an observation. From there, we follow the steps of the scientific method. Remember, the steps of the scientific method are flexible! Observation Ask questions Conduct background research Make a hypothesis/ prediction Test hypothesis/ experiment Record results Analyze results and form a conclusion

The groups involved… A controlled experiment has two different groups: A control group: is the exact same as the experimental group, BUT it doesn’t contain the independent variable (what we are testing for) This group serves as a reference to determine the effectiveness of what we are testing. The Experimental group(s): This group has the exact same characteristics as the control group, but it DOES have the independent variable. This group receives the new treatment, design, etc to test the results of the experimental/ independent variable. This group contains the experiments participants. The number of these participants is called the sample size.

Variables… A controlled experiment contains three different types of variables… The independent variable: the variable/ thing that we are testing The dependent variable: the way we measure the result of the independent variable Therefore, the dependent variable depends on the independent variable The controlled variables: the variables/ factors that are kept constant/ unchanged to ensure the accuracy and validity of the experiment

Lets Look at an Example… Question: which fertilizer works best Control group: plant B Experimental group: plant A Controlled variables: sun, water, age of plant Independent variable: fertilizer Dependent variable: height and health of plant