Nature of Science & Scientific Investigations

The Scientific Method “The Scientific Method” –FORGET IT!!! There isn’t ONE right way to do science! –The Scientific Method –Scientific Methods Not all scientific knowledge comes from “experiments”. –So what do we mean when we say, “experiment”?

Scientific Experiment Type of investigation that asks, “How does x affect y?” Clearly defined independent (test) variable, dependent (outcome) variable, and controlled variables (constants). –Examples: How does the color of a car affect the temperature inside the car? How does the brand of paper towel affect how much water is absorbed?

Independent vs. Dependent Independent (Test) Variable –Variable that is changed on purpose –Variable being tested Dependent (Outcome) Variable –Variable that may or may not be affected by changing the independent variable (it DEPENDS on the IV) –Usually measured or observed Controlled Variables (constants) –Variables that are kept constant (the same) Control Sample –Sample treated like others except without the IV.

How does the type of water affect plant growth? 1. What is the IV? 2. What is the DV? 3. What are some CV’s? type of water plant growth amount of water, sunlight, fertilizer, etc…

Systematic Observation Type of investigation that asks, “What happens when…?” –Ex) “What happens when geese migrate?” Investigator makes a series of observations that lead to inferences about the subject. –No identification of variables (IV & DV) –No control of variables (no constants)

Graphing Your Results Title – should explain what information can be gained from the graph Grid – x and y axis should be appropriately scaled to fit the whole paper and labeled with appropriate units Independent Variable – should be labeled on the x axis Dependent Variable – should be labeled on the y axis Data – should be carefully plotted

Confirmation Search for consistent and predictable results –Does NOT mean we “confirm” that we got the right answer! Repetition & Replication

Repetition When a scientist performs multiple trials of an investigation to make sure he/she is getting consistent and predictable results. Ex: Which type of soil do earthworms like best? –What does it mean if… they like soil A the first time, soil A the second time, and soil A the third time? they like soil A the first time, soil B the second time, and soil C the third time?

Replication When other scientists try to replicate an investigation done by a colleague to see if they get consistent and predictable results. What does it mean if… –they follow your procedures and reach the same conclusion as you? –they follow your procedures and reach a different conclusion than you?

Scientific Knowledge Science is not a list of facts and information to be memorized! –Scientific knowledge changes as new understanding evolves Scientific explanations are based on empirical evidence. –Cumulative body of observations of a natural phenomenon This cumulative

Scientific Knowledge is the result of a great deal of: –Testing and/or Observation –Debate (argumentation) –Confirmation (repetition and replication) Scientific Knowledge

Theory vs. Law Many people have the misconception that a theory is a law that hasn’t been proven yet… This is INCORRECT!!! Scientific theories DO NOT become scientific laws! NEVER…ever…ever –theories and laws are two different things!

Scientific Law A statement about WHAT HAPPENS in nature that seems to be true all the time. A law will tell you… –WHAT is expected to happen every time under certain conditions. A law will NOT tell you… –WHY it happens. Ex: The Law of Gravity –On Earth, in the absence of other forces, objects will fall toward the center of the Earth.

Scientific Theory An EXPLANATION of things or events based on knowledge gained through many observations and investigations. A theory will tell you… –WHY something happens (at least why we THINK something happens) Theories can be used to explain laws. Ex: The Theory of Gravity –There is a force in nature called the gravitational force that causes an attraction between any two objects with mass.

Theory vs. Law So… –Laws describe WHAT happens –Theories explain WHY it happens Sometimes, competing theories offer different explanations for the same law. –What happens then? Scientists test the theories to gather evidence that may support or dispute them If disputing evidence is found, a theory can either be changed or discarded

What is the Purpose of Science? Science is about questioning. –Asking questions –Searching for answers –Discovering new questions Science is ONE of many ways of understanding the world we live in. –But it is limited in what it can help us understand.

What are the Limits of Science? Science Cannot: –Answer questions about the supernatural world. –Understand matters of faith, artistic expression, feeling. Science Can: –Ask/Answer questions about the NATURAL world. –Only understand observable/testable topics.

What are the Limits of Science? Science Cannot: –“Prove” an idea. –Offer a concrete, 100%, no-doubt-about-it answer. Science Can: –Provide evidence that supports an idea. –Provide evidence that disputes an idea. –Offer answers under specific criteria/limitations.

What are the Limits of Science? Science Cannot: –Assume outcomes without testing. –Disregard evidence that does not support a claim. Science Can: –Predict likely outcomes. –Offer explanations to make sense of empirical evidence.

So…What IS Science? Science is a limited discipline that studies only naturally occurring events, while offering natural explanations for the phenomenon under study. The characteristics of science: - Consistent- Predictable - Observable- Testable - Natural- Tentative