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) w 4. Predicting -- stating in advance the result that will be obtained from testing

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.

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 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.