The Nature of Science

Chapter 1: What is Science?

Chapter 2: Science in Action

Chapter 3: Models in Science

Chapter 4: Evaluating Scientific

Explanation

What is Science Science – a way of learning about the

natural world Scientists ask questions about the natural

world, but questions about art, politics, personal preferences, or morality can’t be answered by science.

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

What is Science? Scientific theory: An attempted

explanation for repeatedly observed patterns in the natural world

A rule that describes a pattern in nature is a scientific law (doesn’t explain the “why”)

Systems in Science Scientists study systems – collections of

structures, cycles, and processes that relate to and interact with each other All systems are made up of other systems

THREE branches of Science Life Science – studies living things and how they

interact….examples??? Earth and space systems are studied in Earth Science Physical science studies matter and energy The practical use of science is called technology

Discussion Question What is the difference between a scientific

theory and a scientific law?

A scientific theory explains, and a scientific law describes.

Science in Action The scientific method includes observing,

questioning, and researching; forming an hypothesis; predicting an outcome; investigating; analyzing; forming conclusions, communicating findings; and repeating the process

Scientists infer conclusions based on observations.

Controlled Experiment One type of scientific investigation Factors that can be changed in an

experiment are called variables Constants are variables that remain

unchanged Safety is important or both laboratory and

field scientists

Scientific Processes and Methods 1. Observations/Questioning 2. Measuring, Organizing Data, and

Classifying 3. Hypothesizing -- a testable explanation

based on experience, reading, and/or previous experiments. (NOT A GUESS)

4. Predicting -- stating in advance the result that will be obtained from testing

Scientific Method, cont. 5. Experimenting -- A controlled procedure for

testing a hypothesis Control Group -- all conditions remain constant Experimental Group -- same as control, except for

ONE factor Variable

Independent Variable - condition that changes Dependent Variable - response to changed condition

Data Qualitative ~ descriptive Quantitative ~ numbers

Scientific Method, cont. 6. Analyzing Data

7. Inferring Conclusions (concluding from evidence collected during experimentation)

8. Modeling and Communicating

9. Test and Re-test ~ law or theory formed

Scientific Method, cont. LAW -- general statement that describes a

wide variety of phenomena If a hypothesis describes HOW things happen

and continues to be supported by evidence, it becomes a law.

THEORY -- most probable explanation for a set of data based on best available evidence If a hypothesis describes WHY things happen

and continues to be supported by evidence, it becomes a theory.

Scientific Method -- Example Observations:

Fish populations in Twin Lakes are declining.

The pH (acidity) of the water in the lakes is dropping to 4.2.

One hundred miles west of Twin Lakes is a power plant that is burning tons of coal every year, releasing sulfur dioxide into the air.

Problem

West Branch

Twin Lakes -- Acid Rain Problem

East Branch

Power Plant

100 miles

Questioning/Hypothesizing

Question: Is there a link between the power plant, the pH of the lake, and the fish decline?

Hypothesis: If acid rain falling on Twin Lakes is related to fish reproduction, then increasing acid rain amounts will cause the fish to have poor reproduction.

Experiment Experiment

Twin Lakes is a lake in the mountains that can be divided by a barrier.

A complete inventory will gather baseline data.

One arm of the lake, on the east side of the barrier, will be treated with sulfuric acid to reduce the pH to 4.0.

The west arm of the lake will be left alone, other than monitoring.

Experiment

West Branch

Twin Lakes -- Acid Rain Problem

East Branch

Power Plant

100 miles

No Acid Added Acid Rain Added

Barrier

Results East Branch:

Fish stop reproducing.

West Branch: No change in fish reproduction.

Conclusion The power plant emits sulfur dioxide into

the air which combines with rain to produce acid rain. The addition of this acidic rain to the lakes lowers the pH and causes the fish to stop reproducing. This results in declining fish populations and jeopardizes the survival of the fish.

Models in Science Model – representation of an object or event used

as a tool for understanding the natural world. Models come in THREE basic types:

Physical models can be seen and touched. Computer models can be seen on a computer screen

but not touched. Idea models are concepts that describe how someone

thinks about something in the natural world.

Physical Model

Computer Model

Idea Model

E = mc2

By Leonardo da Vinci

Model Uses Models communicate observations and

ideas Models can test Predictions Models can save time, money, and lives

Can you think of any of these?? Models change over time as new observations

and discoveries are made.

Evaluating Scientific Explanation Critical thinking- using what is known to

decide if new facts should be agreed with or believed

Evaluating the Data Data should be specific and exact Observations should be carefully, accurately,

and completely noted ~science journal Data must be repeatable to be reliable

Evaluating the Conclusions Conclusions should make sense Other explanations should be considered

before a single conclusion is reached Advertising claims should be carefully

analyzed since they are designed to sell products rather than to promote scientific evidence impartially!!!