1

The Nature of Science

2

1–1 What Is Science?

• Science is a process of inquiry, asking questions, which is subject to change and revision.

• The goal of science is to investigate and understand the natural world.

3

• Scientific thinking begins with observation, the process of gathering information about events or processes in a careful, orderly way.

• Observations generally involves using the senses

4

• Inference – a logical interpretation of observations based on prior knowledge and experience

5

Observation vs Inference

• List 3 Observation and 3 Inferences

6

Observation vs Inference

• List 3 Observation

• List 3 Inferences

7

Observation vs Inference

• List 3 Observation

• List 3 Inferences

8

• Two types of data:– Quantitative data: expressed in numbers,

obtained by counting or measuring.– Qualitative data: descriptive and involves

characteristics that can’t usually be counted.

9

1-2 How Scientists Work

SCIENTIFIC METHOD

• While there are no fixed steps, it generally involves:

1) MAKE OBSERVATIONS: observations utilize the senses to gather information.

10

2) ASK A QUESTION: observations may lead to unanswered questions.

3) FORM A HYPOTHESIS: A good hypothesis predicts a relationship between cause and effect.

- A hypothesis is a proposed scientific explanation for a set of observations.

-Scientific hypotheses must be proposed in a way that enables them to be tested.

11

4) SET UP A CONTROLLED EXPERIMENT: A controlled experiment involves two groups:

a) Variable (Experimental) group: A variable is the factor of an experiment that can change.

12

– Controlled (constant) variables: same for both the control and variable group.

– Manipulated (independent) variable: variable that is deliberately changed.

– Responding (dependent) variable: changes in response to the manipulated variable (what happened).

13

b) Control group: group that receives no experimental treatment, the standard against which results are compared.

14

5) RECORD AND ANALYZE RESULTS: keeping a written record of observations and data.

6) DRAWING A CONCLUSION: Use evidence to determine whether the hypothesis was supported or refuted.

15

7) REPORTING RESULTS: Results are only useful if they are made available to other scientists for peer review.

16

But why can’t I test it?

• It isn’t ethical (many animal studies, disease studies, etc.)

• It can’t be controlled

• We lack the technology

17

‘I have a theory’ vs. Scientific Theory

• Common usage of theory = guess, prediction (hypothesis)

• A theory is a well-tested explanation that unifies a broad range of observations.

– No theory is considered absolute truth.

– As new evidence is uncovered, a theory may be revised or replaced.

18

Scientific Laws

• A statement of fact meant to explain, in concise terms, an action or set of actions.

• It is generally accepted to be true and universal, and can sometimes be expressed in terms of a single mathematical equation.

19

• The biggest difference between a law and a theory is that a theory is much more complex and dynamic.

• A law governs a single action, whereas a theory explains an entire group of related phenomena.

20

• A scientific law is like a slingshot. A slingshot has one moving part--the rubber band. If you put a rock in it and draw it back, the rock will fly out at a predictable speed, depending upon the distance the band is drawn back.

• An automobile has many moving parts, all working in unison. An automobile is a complex piece of machinery. Sometimes, improvements are made to one or more component parts. A new set of spark plugs that are composed of a better alloy that can withstand heat better, for example, might replace the existing set. The function of the automobile as a whole remains unchanged.

• A theory is like the automobile. Components of it can be changed or improved upon, without changing the overall truth of the theory as a whole.

ANALOGIES