Understanding Scientific Theories and Laws

1. Modifying Scientific Theories Chapter 2 Lesson 3 Page 68

2. What is a Scientific Theory? • “Theory” can be used loosely to describe an explanation of one or more events • Scientific theory is much more specific • Scientific theory- a well-tested explanation for a wide range of observations and experimental results • Sometimes a large set of related observations can be connected by a single explanation

3. Why are some Theories Modified • “Law”-rule that must be followed • Scientific law- a statement that describes what scientists expect to happen every time under a particular set of conditions. • Example: if you let go of a ball it will fall to the ground. • If something else happens, then something has interfered

4. Scientific Law vs Scientific Theory • Scientific laws and theories each describe observed events but they are very different • A law describes a pattern in nature without attempting to explain it • If the statement is trying to explain why something happens, then it is a theory

5. Modifying Scientific Theories • Laws explain easily observed event, so laws become accepted quickly • Scientists only accept theories when they can explain important observations • If a theory cannot explain an observation, then it is revised or thrown out • (as long as the theory can explain a wide range of observations it is changed instead of being thrown out)

6. Modifying Scientific Theories • As scientists learn more about the natural world, their theories evolve to explain new observations • New observations can lead to new ideas • Theories also change because technology has changed what we are able to observe • Scientific theories change because new technology improves our ability to observe the natural world

7. Answer the questions on pages 68-71