1. The Nature of Science What is Science? How do scientists work?

2. Nature of Science

3. Goal of Science To understand the world around us EX. Does life appear from non-living matter? To explain events by making predictions EX. Life doesn’t appear from non-living matter. To investigate predictions EX. Setting up an experiment to see if life comes from non-living matter, or from living things

4. How scientists work

5. Observations- Gathering evidence It all starts here! Using SENSES to gather data Quantitative: Observation using numbers and measurement Can you make a quantitative observation in this classroom? Qualitative: Observation that doesn’t involve numbers EX. Maggots are on raw meat Can you make a qualitative observation in this classroom?

6. Inferences- Interpreting the Evidence INTERPRETATION based on observation and prior knowledge or experience EX. Maggots come from raw meat. Observation = Maggots are on the meat Prior knowledge = Maggots have always been found on raw meat Can you make an inference about something in the classroom? Observation = Prior knowledge =

7. Hypothesis- Explaining the Evidence The answer to a “BURNING QUESTION”! Only useful if it can be tested! Evidence must be gathered and tested. Example: Question = Do living things come from non-living matter? Hypothesis = Living things do not come from non-living things. We now must set up an investigation to test our hypothesis!!!! What is the process called that scientists use? SCIENTIFIC METHOD!

8. The Scientific Method 1.State the problem (the burning question) 2.Form a hypothesis (answer to burning question) 3.Design a controlled experiment 4.Collect organized data 5.Analyze data 6.Form a conclusion (Was your hypothesis correct?) 7.Peer evaluation (Can your experiment be retested and always get same results?)

9. Definitions Variable: Things that can be manipulated or changed by scientist during experiment A controlled experiment tests ONE variable Independent: (Manipulated variable) Manipulated by scientist Graphed on X-axis Dependent: (Responding Variable) Responsive variable (tested against independent) Graphed on Y-axis Controlled Variables: Things that must be kept constant during experiment If altered, can be used to show error in experiment

10. Setting up a Controlled Exp.

11. 1 st Step – Ask a Question

12. Redi’s Experiment: Scientific Method at work! 1.Problem: How do living things arise? 2.Hypothesis: Old view: Living things arise spontaneously from non-living matter. (spontaneous generation) Maggots arise spontaneously on raw meat. New idea (proposed by Francesco Redi): Living things come from living things. Maggots come from flies that land on the meat.

13. 2 nd Step – Form a Hypothesis

14. Redi’s Experiment: Scientific Method at work! 3.Design a controlled experiment to test hypothesis Redi used two jars, each with meat. One jar covered with gauze, one jar without gauze. Can you list the things that need to be kept constant (controlled variables)? Type of meat, type of jar, temperature, length of exposure Can you name the independent variable? gauze Can you name the dependent variable? maggots

15. 3 rd Step – Design and Conduct Exp.

16. Redi’s Experiment: Scientific Method at work! 4.Collect data: Written, drawings, etc… Redi’s data: Jar with no gauze = maggots Jar with gauze = no maggots 5.Analyze data: Redi figured that the gauze prevented flies from landing on the meat 6.Draw a conclusion: Redi’s hypothesis was correct. Living things do come from living things. 7.Peer evaluation***** Redi’s experiment was tested and retested by others including Louis Pasteur

17. Step 4 – Analyze Results

18. Step 5 – Draw a Conclusion