November 14, 2014 Objectives: ◦ Differentiate between independent variables, dependent variables, and constants ◦ Explain how to carry out a scientific experiment Journal: ◦ What do you think the steps are to carrying out a scientific experiment?

Designing a Scientific Experiment

Scientific Methods of Investigation Begin with a question to be answered Form a hypothesis Design the experiment Carry out the experiment and gather Data Analyze data Draw conclusions

Controlled Experiments A procedure that tests one factor at a time by using a control and an experimental group Example: ◦ Testing the affect of sunlight on plant growth

Hypothesis An “If…Then…” statement that predicts what you think the outcome of the experiment will be Example for the Affect on Sunlight on Plant Growth: ◦ _________________________________

Two Groups Control Group ◦ Serves as a basis for comparison ◦ Receives no experimental treatment Experimental Group ◦ Identical to the control group except for the one factor that the experimenter is manipulating Example for the Affect on Sunlight on Plant Growth ◦ Control Group – ____________________ ◦ Experimental Group - _________________

Experimental Variables Independent variable ◦ Also known as the manipulating variable ◦ The one thing the experimenter is actually changing Dependent variable ◦ Also known as the responding variable ◦ The factor that changes in response to the independent variable Example for the Affect on Sunlight on Plant Growth ◦ Independent Variable – __________________ ◦ Dependent Variable - ___________________

Constants Everything else besides the independent variable should stay the same between the two groups Example of Constants for the Affect on Sunlight on Plant Growth - __________

Number of Individuals in Each Group Equal number of individuals in each group Large sample sizes

Number of Trials The more trials you have, the more reliable your data will be

Data Analysis and Conclusions Scientists then analyze the results and draw conclusions from them