What is Science 8-24 and 8-25

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Welcome to Class!

8-24 and 8-25

Complete the following:

 Take out Syllabus and lab safety contract signature

 Take out Lab safety quiz online

 Take out Journal with Cornell notes for Homework grade (be sure to Enter new entry as well as label the page you took notes on for today “What is Science?”)

 Glue in vocabulary #1 next available page

Agenda

 Revisit materials learned from last week

 Lecture notes on What is Science?

 Kahoot interactive Quiz

 Create Flow Map of Scientific Method

 Concept map compare and contrast Hypothesis vs.

Theory

 Homefun: Assigned Vocabularies

What Is Science?

The Nature of Science

Science

 Uses evidence to construct testable explanations and predictions of natural phenomena

 Generates knowledge

Beginnings of Biology

• Many of the original understandings of life came from philosophers who did not actually conduct experiments, rather using logic and reason.

• Aristotle, an influential Greek philosopher, proposed that life could arise from non-living matter.

So with animals, some spring from parent animals according to their kind, whilst others grow spontaneously and not from kindred stock; and of these instances of spontaneous

generation some come from putrefying earth or vegetable matter, as is the case with a number of insects, while others are spontaneously generated in the inside of animals out of the secretions of their several

organs.

—Aristotle,

History of Animals, Book V, Part 1

Scientific Method

• The idea of spontaneous generation was eventually discarded through the use of the scientific method.

Scientific methodology involves:

– observing and asking questions,

– forming hypotheses

– conducting controlled experiments,

– collecting and analyzing data

– drawing conclusions.

• Scientific investigations begin with observation , the act of noticing and describing events or processes in a careful, orderly way.

• A hypothesis is an explanation for an observation based on prior knowledge.

– Aristotle’s idea of spontaneous generation began with the observation that maggots would arise from meat or dead flesh, fleas from dust, tapeworms from other organisms, etc.

• During Aristotle’s time, all scientific ideas were based on thought and logic, not experimentation.

• Experiments test a hypothesis under controlled conditions.

– Whenever possible, a hypothesis should be tested by an experiment in which the independent variable is changed.

– The variable that is changed or affected is called the dependent variable , and will be measured.

– Any other variables should be held unchanged or constant .

• All experiments involve the collection of data.

– If this includes numerical measurements (time, distance, etc), the data is quantitative .

– If this includes nonnumerical descriptive observations, the data is qualitative .

• An Italian physician named Francisco Redi proposed an experiment to test spontaneous generation.

– A flask containing raw meat was left in the open. This was the control group , since no new variable was being introduced.

• Two additional flasks were set up, one completely sealed, and the other covered with gauze to allow air flow.

– These were the experimental groups that were being exposed to the independent variable.

– The dependent variable, the appearance of maggots, was recorded.

• Only the unsealed flask grew maggots. Redi’s conclusion was that his hypothesis was correct -maggots did not spontaneously generate, but grew from tiny eggs laid by flies.

– Conclusions always indicate whether the original hypothesis is supported or rejected.

Sources of Error

• Accounting for every single variable in a scientific study is nearly impossible. There are many factors that can cause error or otherwise cause an incorrect conclusion.

• Probability helps to predict the likeliness of an experimental result occurring simply due to random chance.

– The effects of random chance are countered with having a large sample size in the experiment.

• Another major problem with experiments is when scientists or patients influence the data to produce a specific result.

– This is called bias .

• Depending on the results of the experiment, the hypothesis may be rejected or modified.

• New experiments may be designed and conducted until some version of the hypothesis is supported.

• Hypotheses should not be confused with theories , which are large, broad explanations composed of many hypotheses and experimental results.

– A theory would not be rejected by a single experiment, but a hypothesis could be.

– An example of a theory is the germ theory, which states that some diseases are the result of the presence and actions of microorganisms within the body.

Scientific Methodology: Observation

Science is a general style of investigation, not a rigid step-by-step process.

Scientific Methodology: Asking Questions

Why do marsh grasses grow to different heights in different places?

Scientific Methodology: Hypothesis

what scientists already know

Inference: a logical interpretation based on

Hypothesis: a tentative scientific explanation that can be tested further

Scientific Methodology: Experiment

Testing hypotheses often involves designing experiments that measure factors that can change, or variables.

Scientific Methodology: Collecting Data

Quantitative data are numbers.

Qualitative data are descriptive.

Scientific Methodology: Analyzing Data

Data analysis in science often relies on the use of statistics.

Scientific Methodology: Review

Kahoot Quiz

https://kahoot.it/#/

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