1. Do Now 4/30: DO NOT record today’s Do Now – answer on notes Several students are conducting an experiment to test the effect of exercise on heart rate. Students do 20 sit-ups in one minute of exercise. The data chart below shows the heart rate at one-minute intervals for each student. Which of these is the dependent variable? A. time B. heart rate C. type of exercise D. number of sit- ups

2. Dependent Variable = B. heart rate In any experiment, the dependent variable is the measured outcome or result. The independent variable is the variable whose effect is being investigated. What is the independent variable here? Minutes of exercise

3. Theories In science, theory has a very different meaning than in common parlance S H U Y P P O O T R H T E E S D I S S H U Y P P O O T R H T E E S D I S S H U Y P P O O T R H T E E S D I S S H U Y P P O O T R H T E E S D I S S H U Y P P O O T R H T E E S D I S Theory Scientific theories are supported by many different tested hypotheses and observations. A theory describes a broad set of related observations

4. Theory of Evolution by Natural Selection The basic idea of the theory of evolution is that the organisms alive today are the descendents of older organisms. It proposes that new species come about when populations of older species change over long periods of time. It is based on the idea of natural selection: organisms which survive and reproduce the most have more offspring and pass their traits on to the next generation more than less successful ones

5. Example: The deadliest lion has the most offspring…

6. There’s A Dragon in My Garage Read the excerpt from The Demon-Haunted World by Carl Sagan. As you read, consider the question: what makes something scientific?

7. What Makes an Explanation of a Phenomenon “Scientific?” Limited to the observable / measureable Testable / falsifiable

8. The picture above shows the Maryland state fossil, a shell of an ancient species Ecphora quadricostata. What kind of organism do you think it was, and why?

10. Fossil Formation Fossilization is a rare process that occurs under specific conditions (swamps are good for example) They are found in SEDIMENTARY rock, which is deposited layers of soil and organic material smushed together.

11. archaeopteryx

12. Tiktaalik

13. Australopithicus: Lucy

14. Hypothesis we’re testing Hypothesis: The organisms that have inhabited Earth in the past are similar to the ones here now. Prediction: If the organisms that have inhabited Earth in the past are similar to the ones here now, then…we should be able to figure out what type of organisms made fossils that we’ve found.

15. Fossil Exploration There are 9 different fossils at different locations around the room. You will spend about 2-3 minutes examining each one. While at each station, carefully observe the specimen, and make a quick sketch of the fossil organisms. It doesn’t have to be beautiful, just good enough to know which one it is After completing your sketches, finish the chart on your handout. For each fossil, write down what organisms alive today you think are most similar to the fossil.

16. The big idea The organisms found on Earth today are the descendents of organisms that lived long ago.

17. Homework On syllabus