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The Process of Life

The Process of Life. Scientific Method. Observation. Scientists believe: That nature is orderly and measurable That natural laws do not change over time OBSERVATION explains phenomena This principle is called: NATURAL CAUSALITY BUT WAIT- don’t forget there’s always CHANCE!!

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The Process of Life

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  1. The Process of Life Scientific Method

  2. Observation Scientists believe: • That nature is orderly and measurable • That natural laws do not change over time • OBSERVATION explains phenomena • This principle is called: NATURAL CAUSALITY BUT WAIT- don’t forget there’s always CHANCE!! Alexander Flemings discovery of penicillin

  3. You have one minute To observe the picture and formulate a hypothesis about what happened How keen are your observations?

  4. Hypothesis How do I make this guess????? INDUCTIVE vs. DEDUCTIVE Reasoning Inductive reasoning: bottom up approach- observations are made from SPECIFIC TO GENERAL Deductive reasoning: top-down approach- observations are made from GENERAL TO SPECIFIC An educated guess

  5. Inductive Reasoning Allows observer to move from SPECIFIC TO GENERAL • Jill is a teacher • All teachers are smart • Therefore Jill is smart

  6. Deductive Reasoning Allows observer to move from GENERAL to SPECIFIC MOOOOOO • Every vertebrate has a backbone • Cows are vertebrates • Cows have backbones I am a SYLLOGISM – The Syllogism is a specific form of argument that has three easy steps.

  7. A hypothesis must be testable Can these be tested? _____ Bluebird songs are beautiful.
_____ Only male bluebirds sing. 
_____ Sparrows will leave territories where they hear bluebird songs.
_____ Bluebirds hate sparrows.

  8. IF I shake this really hard, THEN I might explode! Experiments An experimental design is proposed that tests the hypothesis Using DEDUCTIVE REASONING scientists formulate an IF…. THEN Statement

  9. Experiments consist of • A control group • Independent variables – a factor that causes an observable change in other variables • Example: someone's age. Other factors (such as what they eat, how much they go to school, how much television they watch) aren't going to change a person's age. • Dependent variables– changes DUE to other factors • Example: a test score, because it could change depending on several factors such as how much you studied, how much sleep you got the night before you took the test, or even how hungry you were when you took it. • (Independent variable) causes a change in (Dependent Variable) and it isn't possible that (Dependent Variable) could cause a change in (Independent Variable).

  10. DATA DATA DATA DATA DATA • Observable • Measurable • Does the DATA show any probability of chance? This is called a “measure of SIGNIFICANCE” • OH NO – Not STATISTICS!! • Statistical significance is the number, called a p-value, that tells you the probability of your result being observed, given that a certain statement (the null hypothesis) is true. If this p-value is sufficiently small, the experimenter can safely assume that the null hypothesis is false. You roll two dice, they both turn up one. This does not fit your hypothesis that you would only roll a one, 1 out of 6 times. Is your data SIGNIFICANT enough to change your prediction?

  11. Conclusion • Does the date SUPPORT or REJECT the hypothesis? • Can I repeat my experiment? • The conclusion of 1 experiment can lead to the beginning of another! • Communicate the results!!

  12. OK, so What’s the Point of all this? • The ultimate goal is to understand the world, using data to support our observations • We call this a: • SCIENTIFIC THEORY or a SCIENTIFIC PRINCIPLE • Let’s look at some well know theories: Cell theory Heliocentric theory Evolution Gene theory Theory of gravity Germ theory

  13. Theory vs. Law Theories become laws---NO—theories explain sets of data (the why) Laws provide general rules for what we expect to happen (the what) A theory IS NOT a lesser form of a law! Theories : Must explain a wide range of observations Must be falsifiable can be changed if new evidence presents itself scientists do not "believe" in something. Instead, they have levels of confidence in explanations for natural phenomena.

  14. Occam's Razor • A paper clip is placed on a scale, the scale reads 600 pounds. The following hypotheses can be proposed: • The paperclip weighs 600 pounds • The scale is broken • There is a miniature black hole producing a gravitational pull on the paperclip at that moment, creating such a force to make the paperclip weigh 600 pounds One last tid-bit! proposed by William Ockham in the 15th century. The simplest explanation is usually the right one!

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