Scientific Method

1. Notes Scientific Method Chapter 1: Section 2 How Scientists Work

2. Scientific Method Definition • The scientific method is- • A logical and systematic approach or process to problem solving.  • An organized way of using evidence to learn about the natural world.

3. Question What does the scientist want to learn more about? First Then Research Gathering of information Scientific Method An Overview Next Hypothesis An “Educated” guess of an answer to the question Then Procedure/ Method Written and carefully followed step-by-step experiment designed to test the hypothesis Next Data Information collected during the experiment And And Observations Written description of what was noticed during the experiment Finally Conclusion Was the hypothesis correct or incorrect?

4. As we all know, frogs have four legs. What’s up with thesefroggies? 1. Observing • Make an observation • See somethingunusual • Frogs withincorrectnumber oflegs!

5. Belief based on prior observations • Redi observed that maggots appeared on meat a few days after flies were on meat • No microscope = no way to see eggs • But Redi believed that maggots came from eggs that were laid by flies

6. Forming a Hypothesis Redi’s Hypothesis: Flies produce maggots. • How could he test this? • Through a controlled experiment

7. Jars with meat Uncovered jars Covered jars Redi’s Controlled Experiment • Redi used two groups of jars • Jars that contained meat and no cover • Jars that contained meat and gauze cover

8. Variables in an Experiment • Variables - Factors that can be changed • Controlled Variables - all the variables that remain constant • Manipulated Variable - (also called the Independent Variable) - factor in an experiment that a scientist purposely changes • Responding Variable- (also called the Dependent Variable) - the outcome or results, factor in an experiment that may change because of the manipulated variable….what a scientist wants to observe

9. Variables in Redi’s Experiment • Controlled Variables: jars, type of meat, location, temperature, time • Manipulated Variables: gauze covering that keeps flies away from meat

10. Two groups of Jars with meat Uncovered jars Covered jars Let’s think about this.… Uncovered jars • Which is the control group? • Which is the experimental group? Covered jars

11. Redi’s Experiment on Spontaneous Generation OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat. HYPOTHESIS: Flies produce maggots. PROCEDURE Covered jars Uncoveredjars Controlled Variables: jars, type of meat, location, temperature, time Several days pass Manipulated Variables: gauze covering that keeps flies away from meat Responding Variable: whether maggots appear Maggots appear No maggots appear CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

12. 6. Collect and Record Data Data: observations and measurementsmade in an experiment Types of Recorded Data • Quantitative - observations that involve measurements/numbers; i.e. 3 days, 12 maggots, 4 g, 13 sec, 8 liters • Qualitative - observations thatdo not involve numbers, are of a descriptive naturei.e. white maggots covered the meat, leaves were all wilting

13. 8. Draw Conclusions • Restate the hypothesis: Example: Flies produce maggots. • Accept or reject the hypothesis. • Support your conclusion with specific, numerical data. • What was Redi’s conclusion? • Flies lay eggs too small to be seen. • Maggots found on rotting meat are produced from the eggs laid by flies. • Maggots are not appearing due to spontaneous generation!

14. S C I E N T IFIC M E T H O D R E V I E W

15. Define the Problem Report Results Analyze Data Make an Observation State the Hypothesis the Problem Can you put these steps in order? 10 8 2 7 6 4 3 1 9 5 Determine Limitations

16. Define the Problem Report Results Analyze Data Make an Observation State the Hypothesis the Problem Steps of ScientificMethod in order 1 4 2 5 3 8 7 9 6 10 Determine Limitations

17. Scientific Theory • A theory is an explanation of a set of related observations or events based upon proven hypotheses and verified multiple times by detached groups of researchers

18. Scientific Law Scientific Method • Scientific laws represent the cornerstoneof scientific discovery • They must be simple, true, universal, and absolute • If a law ever did not apply, then all science based upon that law would collapse