Scientific Processes and Methods w 1. Observations/Questioning w 2. Measuring, Organizing Data, and Classifying w 3. Hypothesizing -- a testable explanation based on experience, reading, and/or previous experiments. (NOT A GUESS) Inductive Reasoning w 4. Predicting -- stating in advance the result that will be obtained from testing Deductive Reasoning (If…then…statement)

Scientific Method, cont. w 5. Experimenting -- A controlled procedure for testing a hypothesis Control Group -- all conditions remain constant Experimental Group -- same as control, except for ONE factor Variable Independent Variable - condition that changes Dependent Variable - response to changed condition Data Qualitative ~ descriptive Quantitative ~ numbers

Scientific Method, cont. w 6. Analyzing Data w 7. Inferring Conclusions (concluding from evidence collected during experimentation) w 8. Modeling and Communicating w 9. Test and Re-test ~ law or theory formed

Scientific Method, cont. w LAW -- general statement that describes a wide variety of phenomena If a hypothesis describes HOW things happen and continues to be supported by evidence, it becomes a law. w THEORY -- most probable explanation for a set of data based on best available evidence If a hypothesis describes WHY things happen and continues to be supported by evidence, it becomes a theory.

Inductive Reasoning w Looks at specific cases or facts and tries to develop a general rule or conclusion. w Used to form a hypothesis. w The validity (truth) of the generalization is not assured (must be tested independently).

Inductive Reasoning, cont. w Example #1: (Valid) Seals are mammals and have fur or hair. Mink are mammals and have fur or hair. Mice are mammals and have fur or hair. People are mammals and have fur or hair. Hypothesis: Mammals have fur or hair.

Inductive Reasoning, cont. w Example #2: (Valid) Doritos are chips and are found in aisle #5. Cheetos are chips and are found in aisle #5. Pretzels are chips and are found in aisle #5. Ruffles are chips and are found in aisle #5. Fritos are chips and are found in aisle #5. Hypothesis: Chips are found in aisle #5.

Inductive Reasoning, cont. w Example #3: (Invalid) Robins are birds and can fly. Sparrows are birds and can fly. Vultures are birds and can fly. Eagles are birds and can fly. Falcons are birds and can fly. Hypothesis: All birds can fly.

Deductive Reasoning w Applies a general rule known to be valid to a specific case. w Conclusion is guaranteed to be valid. w If … then … statement used to study hypotheses.

Deductive Reasoning, cont. w Example #1: Given: All dogs pant when they are thirsty. My dog is panting. Conclusion: My dog needs a drink. w If…Then…: If all dogs pant when they are thirsty and my dog is panting, then she must need a drink.

Deductive Reasoning, cont. w Example #2: Given: All carnivores eat meat. A wolf is a carnivore. Conclusion: A wolf eats meat. w If … Then…: If all carnivores eat meat and a wolf is a carnivore, then wolves eat meat.

Deductive Reasoning, cont. w Example #3: Given: All students love Biology. (Assuming that this is, indeed, an accepted rule!) You are a student. Conclusion: You love Biology. w If…Then…: If all students love Biology and you are a student, then you love Biology!

Scientific Method -- Example w Observations: Fish populations in Twin Lakes are declining. The pH (acidity) of the water in the lakes is dropping to 4.2. One hundred miles west of Twin Lakes is a power plant that is burning tons of coal every year, releasing sulfur dioxide into the air.

Problem West Branch w Twin Lakes -- Acid Rain Problem East Branch Power Plant 100 miles

Questioning/Hypothesizing (Inductive Reasoning) w Question: Is there a link between the power plant, the pH of the lake, and the fish decline? w Hypothesis: If acid rain falling on Twin Lakes is related to fish reproduction, then increasing acid rain amounts will cause the fish to have poor reproduction.

Experiment w Experiment Twin Lakes is a lake in the mountains that can be divided by a barrier. A complete inventory will gather baseline data. One arm of the lake, on the east side of the barrier, will be treated with sulfuric acid to reduce the pH to 4.0. The west arm of the lake will be left alone, other than monitoring.

Experiment West Branch w Twin Lakes -- Acid Rain Problem East Branch Power Plant 100 miles No Acid Added Acid Rain Added Barrier

Results w East Branch: Fish stop reproducing. w West Branch: No change in fish reproduction.

Conclusion w The power plant emits sulfur dioxide into the air which combines with rain to produce acid rain. The addition of this acidic rain to the lakes lowers the pH and causes the fish to stop reproducing. This results in declining fish populations and jeopardizes the survival of the fish.