The Scientific Method

What is the Scientific Method? A series of steps used to answer questions about the world around us…

Steps… 1. Problem/Ask a question Gather Information 2. Hypothesis 3. Experiment 4. Data 5. Results 6. Conclusion 7. Repeat

1. State the Problem o Based on observations o MUST be scientific, NOT an opinion

After 65 million years, no fossil evidence of dinosaurs. o Question: Why did dinosaurs go extinct?

Gather information o Some information is needed before the process can begin. Either the scientist already has some needed information or background research needs to be done. o Collect data o Take measurements

Evidence: Iridium layer, crater, shocked quartz, and tsunami

Crater

Chicxulub Crater

Shocked Quartz

2. Form a Hypothesis o Possible explanation that is based on facts (educated guess!) o MUST be an IF…THEN statement

If shocked quartz and an Iridium layer were found then a meteor striking the Earth must have killed the dinosaurs 65 million years ago by producing a cloud of dust around the earth lowering temperatures. o Could have also been an asteroid or comet.

3. Conduct your Experiment o Test your hypothesis Luis (left) and Walter Alvarez at the K-T Boundary in Gubbio, Italy 1981 looking for evidence of an iridium layer.

Pieces of an Experiment… o Control: a standard to which all the other results can be compared (Before 65 mya, dinosaurs and mammals co-exsited) o Constant: a factor that does not change when other factors do (mammals are found before and after 65 mya in the fossil record)

Independent vs. Dependent Variables The Cretaceous–Paleogene (K–Pg) extinction event,formerly known as the Cretaceous–Tertiary (K–T) extinction o Independent: The variable that is changed by US, the scientist. (looking for evidence of iridiumin the rock record around the globe) o Dependent: The variable that responds to the change in the independent variable. (Finding a layer of iridium, a rare element in earth’s rock 160 times normal around the globe).

4. Record Your Data o Gathered evidence recorded during your experiment

Types of Data… o Quantitative o n* = NUMBERS o 7 days or 3 feet o Qualitative o l* = LETTERS o Greener or taller Chicxulub crater is located under 3,600 feet of sediment The clay around the crater contains an abundance of iridium

o Dust and debris would have covered the earth causing it to cool rapidly. Plants would die from lack of sunlight; animals would die from lack of food. o 3/4 of all species on earth disappeared.

5. Results Summary of the data Can be graphs, charts or sentences

6. Draw Conclusions o What did you learn from doing the experiment? 7. Revise and Retest o Accept or reject your original hypothesis o Why repeat?

Accept hypothesis!! o Became known as the meteorite impact theory or the K-T Extinction v=Dcp0JhwNgmE

Theory vs. Law o Theory: can be tested o Ex. Theory of Plate Tectonics o Law: Proven fact of nature o Ex. Gravity

List the steps of the scientific method and explain why it is important to scientists. Sept. 4, 2013

Bart believes that mice exposed to microwaves will become extra strong. He decides to perform this experiment by placing 10 mice in a microwave for 10 seconds. He compared these 10 mice to another 10 mice that had not been exposed. His test consisted of a heavy block of wood that blocked the mouse food. He found that 8 out of 10 of the microwaved mice were able to push the block away. 7 out of 10 of the non- microwaved mice were able to do the same. Bart and Microwave

What is the control group? A. Mice in the microwave B. Mice not exposed to microwave What is the independent variable? A. Exposure to microwave B. Strength of the mice

A soccer team is holding a car wash to raise money. They are charging a flat rate of $10.00 for each car that gets washed. In this situation, the amount of money raised (revenue) is dependent on the number of cars washed. Therefore, the amount of money raised (revenue) is the dependent variable, and the number of cars washed is the independent variable.