Chapter 1: the Scientific Method

1. Chapter 1: the Scientific Method

2. Bellwork In your notebooks, please respond to the following: 1.) Take a look at your class period’s bread on the back wall. Write your observations. 2.) What do you think makes a good (valid) experiment?

3. Inquiry Inquiryis the search for information and explanation Scientists begin an inquiry investigation with a question What would be a question for our bread/Germ-X experiment?

4. Hypothesis • A suggested solution to the problem/question • Must be testable • Usually written as “If…Then…” statements • Predicts an outcome • Write a hypothesis for the bread experiment.

5. Scientific Experiments Follow Rules • An experimenter changesone factorandobservesormeasureswhat happens

6. The Experiment • The factor that is changed is known as the independent variable(a good/valid experiment changes only one variable at a time!) • The factor that is measured or observed is called the dependent variable

7. The Control Variable • The experimenter makes a special effort to keep other factors constant so that they will not affect the outcome • Those factors are called control variables • Used for comparison • What are the different variables (IV, DV, control) in the bread experiment?

8. One more thing… it is best to make several trials with the independent variable…why?

9. To be a Valid Experiment: • Twogroups are required --- the control & experimental groups • What do you think the difference is between these groups? • There should be only one variable manipulated

10. Types of Data Dataare recorded observations or items of information Data fall into two categories Qualitative, or descriptions, rather than measurements Quantitative, or recorded measurements, which are sometimes organized into tables and graphs What type of data are we using in the bread experiment?

11. Bias • Bias-A preference for or against something • Scientists must be objective(as opposed to subjective) so that their personal preferences, or a biases, do not affect an experiment • Benefits of a double-blind experiment

12. Accuracy vs Precision • Accuracy-Getting the expected number (“accepted value”) • Precision-Getting the same number multiple times What do you think? Can something be precise but notaccurate?

13. Accuracy vs Precision

14. Practice Problems: Accuracy vs Precision 1.) Frank shoots his paintball gun at four targets five times each. He aims for the center of the target. The black spots represent where he hits the target. In which of the following cases did he hit the target with precision, but not with accuracy? 2.)

15. Graphs When you make a graph, ALWAYS include the following: 1.) Graph title Usually in the format of “The effect of (independent variable) on the (dependent variable)” 2.) Label the x-axis 3.) Label the y-axis 4.) Scale the graph appropriately so the majority of the space is used. Don’t have data points floating outside the graph space 5.) A legend (if more than one data set is graphed, use colors to represent the different data)

16. 1.) Along which axis (x or y) is the independent variable? 2.) Along which axis (x or y) is the dependent variable? 3.) Approximately how many bubbles are produced at 20 m?