Introduction to Science

Unit 1

The Nature of ScienceAttempt to answerquestions about thenatural world by:• Exploring the unknown• Explaining the known• Experimenting to test

theories or confirm facts

3 Main Branches of Science

• Biological- Botany, Ecology, Zoology, etc.• Physical- Physics (motion), Chemistry (matter)• Earth- Geology, Astronomy, Meteorology

The Way Science Works: Scientific Method

Steps:1. Making observations2. Asking questions3. Forming a hypothesis; making a prediction4. Testing the hypothesis through experimentation5. Collecting and analyzing data from experiment6. Drawing conclusion(s) from data7. Communicating data to peers or public

Scientific Method (cont’d)• 1 question investigated at a time.• Controlled experiments- compare

experimental group (variable) to control group (lacks variable).

*independent variable= variable/factor tested

*dependent variable= variable measured quantitatively (numbers)

• Experiments can only disprove an hypothesis.

Scientific Thinking

• Inference= conclusion drawn from previous data, not on direct observation.

• Theory= explains why something happens.• Law= describes how something works.

Units of Measurement-System International (SI) Units

Quantity Base Unit Abbreviation

Length

Mass

Time

Temperature

Volume

Metric System(based on 10)

based on powers of 10

Prefix Symbol Meaning Multiply base unit by...

kilo- thousand 1,000

hecta- hundred 1,00

deca- ten 10

-------- BASE UNIT ----------------------------

deci- tenth 0.1

centi- hundredth 0.01

milli- thousandth 0.001

pico- millionth 0.000001 (5 zeros!)

nano- billionth 0.000000001 (8 zeros!)

BIGGERBIGGER

SMALLERSMALLER

Metric Conversions(Only SI units are used to express scientific data)To convert from 1 unit to another:1. Identify given unit; unknown unit.2. Use dimensional analysis to compare known to unknown unit (factor-label method) Ex. How many pounds are in 1000 grams?

• How many meters is 800 km?Know Want

Don’t want

• An object’s mass is 250 kg. What is its mass in grams?

Organizing Data: Graphs1. Line Graph: for continuous data2. Bar Graph: compares similar data for several things3. Pie Graph: compares parts of a whole

Our Ages

Favorite Stores

Car Speed

Graphing Data• Independent Variable: changed by scientist; x-axis• Dependent Variable: “depends” on independent

variable; y-axis

Time

Distance (m)

How to Make a Line Graph

1.Label x-axis with independent variable2.Label y-axis with dependent variable3.Choose increments to represent data on each

axis.4.Plot points.5.Connect points.6.Name graph.

Time (s)

Dist

ance

(m)

Time Distance

0 s 0 m

30 s 2 m

60 s 5 m

90 s 11 m

Scientific Notation• Reduces # of 0’s in very large or small

numbers.• Expresses simple #’s x power of 10. (simple # = 1 - 10)

Write 28750.9 in scientific notation.

1. 2.87509 x 10-5

2. 2.87509 x 10-4

3. 2.87509 x 104

4. 2.87509 x 105

Write 2.87509 x 104 in standard notation

1. 287,509.2. 28750.93. 2875.094. 28.7509

Calculating Scientific Notation (Follow math rules for powers of 10) *multiplication= add powers of 10 **division= subtract powers of 10 ex. 7.2 x 10-9

1.2 x 102

7.2 x 10-9

1.2 x 102

sci notation = 6 x 10 -11

Significant Figures• Number of meaningful digits in a quantity.• Significant figures: 1. Non-zero digits are always significant. ex. 1246 (4 SF) 2. Zeros between nonzeros. ex. 1206 (4 SF) 3. Zeros to right of decimal (“trailing zeros”) ex. 0.1200 (4 SF)

Significant Figures (cont’d)

• Significant figures are not: 1. Space holding zeros in digits less than 1. ex. 0.09060 (4 SF) 2. Trailing zeros in a whole number ex. 83,000 (2 SN)

So…

How many sig figs are in the following: 83000 ____ SN 0.000800 ____ SN 8.800 ____ SN 800 ____ SN

Precision vs Accuracy

Science measurements should be:

• Precise: the degree to which an instrument or process will repeat the same value.

• Accurate: the degree of closeness to true value.

The Correlation Method

• Correlation: associations between 2 events ex: width of a tree ring and drought • Used when experimentation is not possible ex: “What was the Earth’s climate 60 x 10⁸ years ago?”• Do not prove cause and effect relationships

between 2 variables

Scientific Habits of MindTraits of a good scientist:• Skepticism- don’t believe everything they’re

told• Open to new ideas• Honesty (even if their hypothesis is wrong)• Creative • Curiosity

Scientific Models

Models: representations of systems• Physical: 3-D, touchable• Graphical: show positions or amounts (think

maps)• Conceptual: verbal or graphical explanation of

how something works (think concept map, diagrams)

• Mathematical: use numbers and equations (hurricane predictions)

Models (cont’d)

StatisticsStatistics: collection and classification of data (numbers)• Provides info for analysis• Uses mean (average) and • Distribution: arrangement of numbers which creates

a pattern• Probability: the chance something will occur• Risk: probability of an unwanted outcome ex: If you don’t study for your next test, you risk

failing it!

Decision Making

• Process for making knowledgeable decisions• Involves: gathering info and looking at

consequences, considering values:Aesthetic Beautiful or pleasing

Economic Gain or loss of money or jobs

Ethical/moral What is right or wrong

Environmental Protection of natural resources