DO NOW Get your notebooks out (under the board) at your seats!! Turn on your CPS Clicker (WarmUp) Scientific Method A process for understanding nature and its changes in a systematic format. There are actually many scientific methods, depending on the nature of the specific problem under study and on the particular investigator involved. Scientific Method 1. OBSERVE. Make observations on some aspect of the universe. 2. HYPOTHESIZE. Make an If then statement" to explain the observations. 3. PREDICT. Use the hypothesis to predict other aspects of the nature of the universe. 4. TEST. Test the predictions by experiments and/or further observations. 5. MODIFY. If the predictions are not supported, use the experimental results and/or new observations to modify the hypothesis and then repeat steps 3 and THEORIZE. When all the predictions are supported by the experiments and/or new observations the hypothesis becomes a theory. A theory is a conceptual framework that explains existing observations and predicts new ones. Scientific Method Step 1Making observations Qualitative (descriptive) Quantitative (numerical/measurement) Scientific Method Step 2-Formulating a hypothesis (making a prediction) A hypothesis is a possible explanation for an observation. A hypothesis is always testable. A hypothesis is NOT a feeling or opinion! Testable Hypotheses Which of the following hypotheses could be tested? Ty Cobb was a better hitter than Pete Rose Ivory soap is 99.7% pure. Rolaids consumes 47 times its weight in excess stomach acid. The baby is happy because he cries three times a day. Scientific Method Step 3-Performing experiments (testing the hypothesis) An experiment is a planned way to test a hypothesis An independent variable is changed to determine how it will affect the dependent variable. A variable that does not change is a constant. A control is the standard to which test results can be compared. Variables A variable is something that can vary or change in a situation. A statement can have one, two, three or more variables. Identify the Variable Ex. The time it takes to run a kilometer depends on the amount of practice a person does. How many variables are in the ex.? And what are the variables? Identify the variable Variable: Time to run a kilometer Variable: Amount of practice Independent/Manipulated Variable If a variable is deliberately changed in a situation by the experimenter, it is a independent variable. Example EX: The amount of pollution produced by cars was measured for cars using gasoline containing different amounts of lead. What is the independent var.? Independent variable: the amount of lead in the gasoline Dependent Variable The dependent variable is the factor that is caused to change by variation in an independent variable. Example Basketball players are seen to be much taller than average. Dependent Variable The ability to play basketball and be on the team often DEPENDS on being tall. ! Being tall DOES NOT DEPEND on playing basketball! Experimental design 1.Problem? 2.Hypothesis? 3.Independent Variable? 4.Constants & Controls? 5.Dependent Variable? Does root hormone affect the growth of plant seeds? If root hormone is applied to seeds in the proper amount, then the seeds will grow roots faster. Root hormone is the independent variable. The pots, soil, water, light, temperature, and seeds are constant between all groups. The control receives no hormone. The dependent variable is the growth of roots on the seeds.