1. Bell Ringer
1. Take out your notebook.
2. Complete the handout

2. Scientific Theories & Laws
(Page )
Essential Question:
Why are scientific theories modified over time, but rarely discarded?

3. 1 - Scientific Theory
A well-tested explanation for a wide range of observations and experimental results

4. *Well-tested explanation
- Repeated experiments leading to a consensus of agreement amongst investigators

5. *Wide range of observations and experimental results
- Multiple trials leading to similar conclusions

6. *A scientific theory:
*Explains how and why something happens

7. *Recent Theories
- Germ Theory
Theory of Evolution
Theory of Plate Tectonics
Big Bang Theory
Cell Theory

8. 2 – Scientific Law *Tells us what happens.
A statement that describes what scientists expect to happen every time under similar conditions.
*Tells us what happens.

9. *Common Scientific Laws:
Universal Law of Gravitation
Newton’s Laws of Motion
Kepler’s Laws of Planetary Motion
Law of Conservation of Mass and Energy

10. 3 – Modifying Theories
*As scientists learn more about the natural world, their theories evolve to explain their new observations.
*Theory of Continental Drift and Plate Tectonics

11. Read the article : “When does a theory become a law?”
*How is a theory compared to building a house?
*What’s the difference between a theory and a law?
*When does a theory become a law?
*What is the process of an explanation becoming a theory?

12. Conclusion
Quick Write – In your own words, explain why scientific theories are sometimes modified, but rarely discarded?