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Nature of Science

I. What is Science?

A. Science—a way of learning about the natural world

1. Scientists ask questions about the natural world, but questions about art, politics, personal preferences, or morality can’t be answered by science.

2. Answers are uncertain because new knowledge and discoveries are continually being made.

3. Scientific theory—an attempted explanation for repeatedly observed patterns in the natural world

4. A rule that describes a pattern in nature is a scientific law.

B. Scientists study systems—collections of structures, cycles, and processes that relate to and interact with each other.

C. Science is divided into three main branches that study different systems.

1. Life science studies living things and how they interact.

2. Earth and space systems are studied in Earth science.

3. Physical science studies matter and energy.

4. The practical use of science is called technology.

II. Science in Action

A. The scientific method includes observing, questioning, and researching; forming an hypothesis; predicting an outcome; investigating; analyzing; forming conclusions, communicating findings; and repeating the process.

B. Scientists infer conclusions based on observations.

C. A controlled experiment is one type of scientific investigation.

1. Factors that can be changed in an experiment are variables.

a. Independent (Manipulated) variable is the variable the scientist changes or manipulates.

b. Dependent (Responding) variable is the variable is an experiment that changes in response to the change in the independent variable.

c. DRY MIX- Dependent or Responding Variable is found on the Y-axis. Manipulated or Independent Variable is found on the X-axis.

2. Constants are variables that remain unchanged.

D. Safety is important for both laboratory and field scientists

III. Models in Science

A. Model—representation of an object or event used as a tool for understanding the natural world

B. Models come in three basic types.

1. Physical models can be seen and touched.

2. Computer models can be seen on a computer screen but not touched.

3. Idea models are concepts that describe how someone thinks about something in the natural world.

C. Models have several uses.

1. Models communicate observations and ideas.

2. Models can test predictions.

3. Models can save time, money, and lives.

D. Models change over time as new observations and discoveries are made.

IV. Evaluating Scientific Explanation

A. Critical thinking—using what is known to decide if new facts should be agreed with or believed

B. Data should be evaluated.

1. The data should be specific and exact.

2. Observations should be carefully, accurately, and completely noted.

3. Data must be repeatable to be reliable.

C. Conclusions should be evaluated.

1. Conclusions should make sense.

2. Other explanations should be considered before a single conclusion is reached.

D. Advertising claims should be carefully analyzed since they are designed to sell products rather than to promote scientific evidence impartially.

V. Description and Measurement

A. Measurement—describes world using numbers

1. Types of measurement—distance, time, speed, volume, mass

2. Measurement can also help describe events.

B. Approximated measurement based on previous experience is estimation.

1. Estimation is useful when actual measurements are not easily made.

2. Estimation can check that an answer is reasonable.

3. When you estimate, you often use the word about.

C. Precision and accuracy

1. Precision—a description of how close measurements are to each other

a. Used to discuss number of decimal places a measuring device can measure

b. Degree of Precision—today’s measuring devices are more precise.

2. Accuracy—comparison of measurement to actual value

3. Precision and accuracy are important in many medical procedures.

4. Measurements can be rounded when precision is not needed.

5. Significant digits—reflect true precision of a calculation

a. Multiplication or division—measurement with the fewest digits determines the number of significant digits.

b. Addition or subtraction—significance determined to the place value of the least precise measurement

VI. SI Units

A. The International System—SI units, in multiples of ten, provide a standard of consistent measurement for global science, business, and industry.

B. Length—the distance between two points; SI unit—meter

1. Measure pencil—use centimeters

2. Measure distance from New York to Chicago—use kilometers

C. Volume—amount of space an object takes up; SI unit—cubic meter

1. To find volume of regular shape—measure length, width, and height and multiply

2. To find volume of irregular shape—volume by immersion

D. Mass—amount of matter in an object; SI unit—kilogram

E. Weight—measurement of force; SI unit—newton

F. Temperature—measure of kinetic energy in particles of matter; SI unit—kelvin

G. Time—interval between two events; SI unit—second

H. Rate—amount of change of one measurement in a given amount of time

VII. Drawings, Tables, and Graphs

A. Scientific Illustrations—often make information more clear than written text can

1. Drawings—can emphasize only necessary details or show things you can’t see

2. Photographs—show an object exactly as it is at a single moment

B. Tables—display information in rows and columns for easier comprehension

C. Graphs—collect, organize, and summarize data visually

1. Line graph—shows relationship between two variables, which must be numbers

2. Bar graph—uses bars of different sizes to show relationships between variables; one variable is divided into parts; the other variable is a number

3. Circle graph—shows parts of a whole as percentages 4. Scales on graphs must be carefully constructed and analyzed so users easily understand the information.