What is A Real Hypothesis?

Hypothesis: a possible explanation for a set of observations or a possible answer to a scientific question To be useful, a hypothesis must be testable with a controlled experiment Controlled experiments also include a control: one condition that is held constant for use in comparison in an experiment

Variables A controlled experiment tests one variable at a time Variable: A factor in an experiment that can change 2 Types of variables: 1. Independent variable: a factor that is changed in an experiment Also called the Manipulated Variable 2. Dependent variable: a factor that is observed or measured in an experiment Also called the Responding Variable

Underline the independent variable and circle the dependent variable in the examples below. If heart rate is related to exercise, then the more strenuous the exercise, the higher the heart rate If Calcium is related to bone density, then people who consume the most Calcium will have the highest bone density

Formalized Hypotheses Hypotheses use the words “if” and “then” Independent & dependent variables should be included in both the “if” and the “then” section Re-read to yourself as if to say… “If ___ is related to ____, then… make a predication.”

Re write these simple predictions into a formalized hypothesis Re write these simple predictions into a formalized hypothesis. Underline the independent variable and circle the dependent variable. 1. Chocolate may cause pimples 2. Ultraviolet light may cause cancer 3. Bacterial growth may be affected by temperature

If consuming chocolate causes pimples, then people who consume a lot of chocolate will have a lot of pimples. If UV light causes cancer, then people with a higher exposure to UV light will be more likely to contract cancer. If bacterial growth is affected by temperature, then bacterial growth will be highest at higher temperatures.