The Scientific Method K (What I know)W (Want to know)L (What I learned) Warm up- take out a piece of paper and do the “K” and the “W” for the above topic.

California State Standards I&E 1f – Distinguish between hypothesis and theory as scientific terms I&E 1k – Recognize the cumulative nature of scientific evidence I&E 1n – Know that when an observation does not agree with an accepted scientific theory, the observation is sometimes mistaken or fraudulent and that the theory is sometimes wrong.

Scientific Method 1 Main Ideas Details Possible explanation for an event or solution to a problem, which is based on information. What is a Hypothesis? Laws only tell you what happens, while theories tell you why they happen. Explanation of some aspect of the natural world that is shown by facts and laws. A theory that has survived many tests and is accepted at true. What is a Theory? What is a Scientific Law?

The Scientific Method 10 Main Ideas Details The Scientific Question States what you are trying to find out. States what you are trying to find out. “What happens if” or “Why?” “What happens if” or “Why?” Identifies the subject of the research AND keeps you focused on that topic. Identifies the subject of the research AND keeps you focused on that topic. The Scientific Question is not the same as the Hypothesis. The Scientific Question is not the same as the Hypothesis.

Scientific Method 2 Main Ideas Details 1. Stating a Problem 2. Gathering Information 3. Form a Hypothesis 4. Test the Hypothesis (Collect Data) 5. Drawing Conclusions 6. Reporting Results Scientific Method Not a smooth path. Can lead you to places you didn’t expect.

Scientific Method 3 Main Ideas Details Control Group and Experimental Group Two groups of a controlled experiment. All the variables between the control group and the experimental group are the same, except the experimental group has one variable, called the independent variable, that is different. Three types of variables Independent variable: the variable that is changed in the experiment. In an experiment there is only one independent variable. Dependent variable: the changes in response to the changes made in the independent variable.

Scientific Method 3 Main Ideas Details Three types of variables (continued) Control variables – every other factors in an experiment that are constant and unchanged.

Scientific Method 4 Main Ideas Details Dr. Walter Alvarez Investigating sedimentary rocks at the Cretaceous – Tertiary boundary (K-T) – a gap in geologic time when Dinosaurs became extinct. LOTS OF FOSSILS NO FOSSILS A FEW FOSSILS Clay layer at K-T boundary had lots of iridium in it. Iridium is rare in normal rocks, but found in meteorites

Scientific Method 5 Main Ideas Details Where else is abundant iridium found? A New Problem Iridium also found at the K-T boundary in many places around the world. A New Problem Why is iridium found in all those places at the K-T Boundary? Data

Scientific Method 6 Main Ideas Details A New Hypothesis Data: Iridium might come from volcanic eruptions –Iridium might come from volcanic eruptions – K-T boundary was the only place with high iridiumK-T boundary was the only place with high iridium Volcanic eruptions produce only a little iridium.Volcanic eruptions produce only a little iridium. Data:

Scientific Method 7 Main Ideas Details An impact from an asteroid or comet would have spread iridium in the atmosphere to be deposited over a large area. A New Hypothesis Where is the crater? A New Problem Other Geologists became interested in finding the crater. Crater should be 150 – 200 km in diameter Data: No craters were the right age and size.No craters were the right age and size.

Scientific Method 8 Main Ideas Details K-T sites in US found had quartz grains that had were “shocked” by impact. This data shows that crater is on continent.K-T sites in US found had quartz grains that had were “shocked” by impact. This data shows that crater is on continent. More data … K-T site found in Haiti. Looked different. Was thick & mixed up. Caused by a tsunami. Crater must be on ocean floor.K-T site found in Haiti. Looked different. Was thick & mixed up. Caused by a tsunami. Crater must be on ocean floor. Which was right???

Scientific Method 9 Main Ideas Details Since deposit in Haiti was thick, crater must be in the Caribbean area. Investigations focused in that area. A New Hypothesis Circular patterns in the rocks found on the north coast of Yucatan. Half on land, half on the ocean floor.Circular patterns in the rocks found on the north coast of Yucatan. Half on land, half on the ocean floor. Yucatan Caribbean

Scientific Method 10 Main Ideas Details Ring structure of Yucatan had been explored and sampled for oil, but none was found.Ring structure of Yucatan had been explored and sampled for oil, but none was found. Samples showed that ring structure could have only been caused by impact.Samples showed that ring structure could have only been caused by impact. Mexican geologists had known about the crater for 30 years: Since this data had never been published, no one knew about it.Since this data had never been published, no one knew about it.

Scientific Method 11 Main Ideas Details The pieces came together: An investigation about sediments in Italy led Dr. Alvarez on a 10 year around-the-world quest. Time and time again, new data led to new problems, which led to new data. The Scientific Method allowed Dr. Alvarez (and many other geologists) to finally determine the cause for the extinction of the dinosaurs and the location of the Crater of Doom.

Scientific Method Main Ideas Details Summary – Highlight (or underline) the important parts of your notes and write a 3 to 5 sentence summary.