Chapter 2 Scientific Method

Essential Questions 1.How do scientists use the scientific method? 2.What is the difference between a theory and a law?

Discovery Science Describes nature  Observation: the use of the senses to gather information  Data: recorded observations  quantitative: recorded as measurements  qualitative: descriptions  Inference: conclusion based on observations

Scientific Method Steps

Observations and Questions  Under what conditions do potatoes usually grow?  Is light necessary for the sprouting of a potato?  How will you tell whether or not light is necessary?

Hypothesis  If… then…  If a potato half was placed in the sunlight for a week, then…

Experiment  Test the Hypothesis!  A potato is cut in half, and the eyes are counted.  The potato halves are each placed in a plastic bag with a wet paper towel.  One will be placed on the windowsill and the other in a dark cabinet for one week.  Control: the constant or basis for comparison  Potato in the dark  Variable: the thing being tested  Affect of light  Dependent Variable: dependent on the independent variable (ex. reaction)  Independent Variable: constant change (ex. time)

Analyze the Results  Look at all data. Graph results, make tables, etc. Do not come up with a reason just yet!  Count the number of sprouts for each and enter in the table.

Draw a Conclusion  After reading the data, now decide whether the hypothesis was true or not. Then give reasons why with supporting evidence.  The hypothesis was __________ because …

Theory A THEORY explains all things that are known about a broad subject and is strongly supported by evidence. Example : evolution Law: theories that have passed many tests and have never been disproven Example: Law of gravity