1. Introduction to Science
Chapter 1

2. The Nature of Science Scientists try to answer questions about the
natural world by:
Exploring the unknown
Explaining the known
Experimenting to test theories or confirm
facts

3. 3 Main Branches of Science
Biological- Botany, Ecology, Zoology, etc.
Physical- Physics (motion), Chemistry (matter)
Earth- Geology, Astronomy, Meteorology

4. The Way Science Works: Scientific Method
Used to learn about the natural world; includes the
following steps:
Making observations
Asking questions
Forming a hypothesis; making a prediction
Testing the hypothesis through experimentation
Collecting and analyzing data from experiment
Drawing conclusion(s) from data
Communicating data to peers or public

5. Scientific Method (cont’d)
Only 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.

6. Scientific Thinking
Inference= conclusion drawn from previous data, not on direct observation.
Theory= explains why something happens.
Law= describes how something works.

7. Units of Measurement- System International (SI) Units
Quantity
Base Unit
Abbreviation
Length
meter m
Mass
kilogram kg
Time
second s
Temperature
Kelvin K
Amount
mole
mol

8. Metric System (based on 10) based on powers of 10
Prefix
Symbol
Meaning
Multiply base unit by...
giga- G
billion
1,000,000,000
mega- M
million
1,000,000
kilo- k
thousand
1000
BASE
UNIT
deci- d
tenth
0.1
centi- c
hundredth
0.01
milli- m
thousandth
0.001
pico- u
millionth
(5 zeros!)
nano- n
billionth
(8 zeros!)
BIGGER
SMALLER

9. 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?

10. How many meters is 800 km?
Know
Want
Don’t want

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

12. Organizing Data: Graphs
Line Graph: for continuous data
Bar Graph: compare similar data for several things
Pie Graph: compare parts of a whole
Favorite Stores
Car Speed
Our Ages

13. Graphing Data Independent Variable: changed by scientist; x-axis
Dependent Variable: “depends” on independent variable; y-axis
Distance (m)
Time

14. How to Make a Line Graph Label x-axis with dependent variable
Label y-axis with independent variable
Choose increments to represent data on each axis.
Plot points.
Connect points.
Name graph.
Distance (m)
Time (s)

15. Time
Distance
0 s
0 m
30 s
2 m
60 s
5 m
90 s
11 m

16. Scientific Notation Reduces # of 0’s in very large or small numbers.
Expresses simple #’s x power of 10.
(simple #- 1 < number < 10)

17. Writing Scientific Notation
1. Identify first number between 1 and Place decimal after that number. 3. Count number of places the decimal had to move- this is the exponent of 10. ex. 210,000,000,000,000,000,000,000 m 2.10,000,000,000,000,000,000,000 m (decimal was moved 23 places to the left) sci notation= 2.1 x 1023

18. Writing Scientific Notation (cont’d)
If decimal moves to right, exponent is negative (original number is less than 1)
If decimal moves to left, exponent is positive
(original number is 1 or greater)
ex cm
0x cm
(decimal was moved 8 places to the right)
sci notation = x 10-8 cm

19. Write 28750.9 in scientific notation.
x 10-5
x 10-4
x 104
x 105

20. Write 2.87509 x 104 in standard notation
287,509.

21. Calculating Scientific Notation
(Follow math rules for powers of 10)
*multiplication= add powers of 10
**division= subtract powers of 10
ex x x 102
7.2 x x 102
sci notation = 6 x

22. Significant Figures Number of meaningful digits in a quantity.
Significant figures are:
1. Any # that is not a zero.
ex (4 SF)
2. Zeros between nonzeros.
ex (4 SF)
3. Zeros to right of decimal
ex (4 SF)

23. Significant Figures (cont’d)
Significant figures are not:
1. Zeroes after nonzeros unless a decimal is
present.
ex. 80,000 (1 SF)
ex. 83,000 (2 SN)
ex (5 SN)
ex (5 SN)

24. Putting It All Together: Chewing Gum
I’ve noticed that when I chew gum, the size changes.
How does the amount of time gum is chewed affect the mass?
Looking through the literature on gum, I see that others have noticed what I’ve noticed, but no one has done an experiment on this.

25. My hypothesis: I think the gum will get smaller as it gets chewed because the sugar will dissolve.
I create an experiment where I time chewing gum and weighing it at different intervals.
I perform the experiment and collect data
YOU will do this in the lab!