22 Sept. 2010
Take out homework: Week 2/3
Homework p. 3 Analysis for graphs
 Objective: SWBAT determine the
precision and accuracy of data.
 Do now: Imagine you are a very accurate
shot with a bow and arrow. Draw a
picture to show what your target looks
like at the end of practice.

Agenda
Do now
2. Go over HW: Analysis of graphs
3. Notes and examples of precision and
accuracy
Homework:
 Week 2/3 Homework p. 3 Conclusions: Fri.
 Conclusion for Density of Pennies Lab: Fri.
 Week 3 Homework: Fri.
 Lab report: Weds.
1.
SWBAT determine the precision and accuracy of data.
Precision and Accuracy
precision: how close a series of
measurements are to each other.
 accuracy: how close a series of
measurements are to the actual or true
value.

SWBAT determine the precision and accuracy of data.
SWBAT determine the precision and accuracy of data.
Volume of a sample of water
(Actual volume: 5 mL)
a.
b.
c.
d.
2.0 mL, 2.1 mL, 1.9 mL
4.0 mL, 5.0 mL, 6.0 mL
1.2 mL, 5.5 mL, 10.6 mL
4.9 mL, 5.0 mL, 5.0 mL
SWBAT determine the precision and accuracy of data.
Mass of copper cylinder (g)
Massing 1
Massing 2
Massing 3
Massing 4
Danika
47.45
47.39
47.42
47.41
Josh
47.95
47.91
47.89
47.93
Larissa
47.13
47.94
46.83
47.47
Three students made multiple weightings of a copper cylinder,
each using a different balance. The correct mass of the cylinder
had previously been determined to be 47.32 grams. Comment
on the accuracy and precision of each student’s measurements.
SWBAT determine the precision and accuracy of data.

Comment on the accuracy and precision of
these basketball free-throw shooters:
 a. 99 of 100 shots are made
 b. 99 of 100 shots hit the front of the
rim and bounce off
 c. 33 of 100 shots are made, the rest
miss.
SWBAT determine the precision and accuracy of data.
Percent Error: a measurement of
how accurate your data are
your _ value  actual _ value
100
actual _ value
1.
2.
So, if the actual value is 5.0 grams, but
your average mass was 4.6 grams, what is
your percent error?
What if your average volume was 25.0
mL, but the actual value is 23.9?
Homework




Week 2/3 Homework p. 3 Conclusions: Fri.
Conclusion for Density of Pennies Lab: Fri.
Week 3 Homework: Fri.
Lab report: Weds.
24 Sept. 2010
Take out homework: Week 3 HW
 Objective: SWBAT convert between units
in the SI system and review for a quiz!
 Do now: My actual mass is 59.1 kilograms.
I weighed myself on three different scales
at the gym, and got the following masses:
 64.9, 65.0 and 65.2 kg.
 Are these masses accurate, precise, both
or neither, and WHY?

Agenda
Do now
II. Homework Check: Week 3 HW
III. Converting SI units
IV. Review Stations
Homework:
Finish Week 2/3 Homework
Quiz Monday.
Bring your book!! (see me after school if
you need a book)
I.
Converting between SI units

notes from the board
SWBAT convert between units in the SI system.
SI Unit Prefixes
Steps to Conversions
1.
2.
3.
4.
5.
6.
7.
Identify and write your known and
unknown.
Choose an equality.
Make a fraction
Put units to cancel on the bottom
Put units to remain on the top
Cancel units and compute
Report answer with units!
Practice Problems
1 liter = 1000 milliliters
1. How many liters are equal to 550
milliliters?
2. How many milliliters are equal to 3.5
liters?
3. How many liters are equal to 45,000
milliliters?
4. How many milliliters are equal to 354
liters?

SWBAT convert between units in the SI system.
1 meter = 100 cm, 1 kilometer = 1000 meters
1. How many meters are equal to 500
centimeters?
2. How many centimeters are equal to 850
meters?
3. How many meters are equal to 37.5
kilometers?
4. How many centimeters are equal to 5.8
kilometers?

SWBAT convert between units in the SI system.
Homework
Finish Week 2/3 Homework
Quiz tomorrow
Bring your book!! (see me after school if
you need a book)
 Lab report: Weds.
SWBAT convert between units in the SI system.
23 Sept. 2010
Take Out: Week 2/3 Homework
You need a calculator and your book.
 Objective: SWBAT show what you know
about Thinking Like a Scientist.
 Do now: How many meters are equal to
37.5 kilometers?
(1 kilometer = 1000 meters)

Agenda
Do now
II. Homework Check
III. Quiz
IV. Physical properties and changes:
textbook reading
Homework: Finish Textbook Analysis
Classwork and Homework: Mon.
Lab Report: Tues.
I.
Quiz Expectations
Work silently and on your own.
 Raise your hand if you have questions.
 When you finish, flip your quiz over.
 Begin working on the textbook analysis
classwork.

Homework
Finish Textbook Analysis Classwork and
Homework: Mon.
Lab Report: Tues.
Please bring a calculator EVERY day!
24 Sept. 2010
Grab your clicker!
Take Out Homework: Textbook Analysis
Objective: SWBAT identify and round a
number to the correct number of
significant figures.
Do now: What is the difference between
chemical and physical changes?
SWBAT identify and round a number to the correct number of significant figures.
Agenda
Do now
II. Homework check
III. Notes: Significant Figures
IV. Practice Problems
V. Conversions problems with significant
figures
Homework: Sig. Fig. and Rounding
Worksheet
Lab report: Tues. (typed)
I.
SWBAT identify and round a number to the correct number of significant figures.
An engineer was responsible for calculating
amount of water that overflowed from a
dam. He measured all of the water runoff
going into the reservoir (1.2 million cubic
feet per year), the rainfall (860 cubic feet per
year), and the capacity of the reservoir (3.8
million cubic feet). He did some fancy
calculations. He reported to his boss that the
overflow from the dam would be
350,246.2544330 cubic feet per year.
 What’s wrong here?

SWBAT identify and round a number to the correct number of significant figures.
SIGNIFICANT FIGURES
Rules for determining how many digits to round to
I. Significant Figures
aka: Significant Digits

A. Nonzero integers count as significant
figures
 Ex. Any number that is NOT zero (1, 2, 3,
4, 5, 6, 7, 8, 9)
 345
 597.2
 145.456
SWBAT identify and round a number to the correct number of significant figures.

Zeros
 B. Leading zeros that come before all the
nonzero digits do NOT count as
significant figures
 Ex: 0.0025 has two sig. fig. The zeros
are “leading” and do not count.
 0.23
 0.0004
 0.03564
SWBAT identify and round a number to the correct number of significant figures.
 C.
Captive zeros are between nonzero
digits and DO count as sig. fig.
 Ex: 1.008 has four sig. fig. The zeros are
captive and DO count.
 10,004
 1.000006
 1,000,000,000,000,567
SWBAT identify and round a number to the correct number of significant figures.









D. Trailing zeros are to the right end of
the number and DO count as sig. fig. if
the number contains a decimal point.
Ex.: 100 has only one sig. fig. because
the trailing zeros DO NOT have a
decimal point.
Example: 1.00 has three sig. fig.
because the trailing zeros DO have a
decimal point.
1.000000
3,000,000
3.00000
30.00
300
300.
SWBAT identify and round a number to the correct number of significant figures.

E. Exact numbers
 Any number found by counting has an
infinite number of significant figures.
 Ex: I have 3 apples. The 3 has an
infinite number of significant figures.
 50 people
 100 baseballs
SWBAT identify and round a number to the correct number of significant figures.
Which are exact numbers?
1.
2.
3.
4.
5.
6.
The elevation of Breckenridge, Colorado
is 9600 feet.
There are 12 eggs in a dozen.
One yard is equal to 0.9144 meters.
The attendance at a football game was
52,806 people.
The budget deficit of the US government
in 1990 was $269 billion.
The beaker held 25.6 mL of water.
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures?
256
1.
2.
3.
4.
1
2
3
4
94%
6%
1
0%
2
0%
3
SWBAT identify and round a number to the correct number of significant figures.
4
How many significant figures?
647.9
1.
2.
3.
4.
1
2
3
4
100%
0%
1
0%
2
0%
3
SWBAT identify and round a number to the correct number of significant figures.
4
How many significant figures?
647.0
1.
2.
3.
4.
1
2
3
4
83%
17%
0%
1
0%
2
3
SWBAT identify and round a number to the correct number of significant figures.
4
How many significant figures?
321.00
1.
2.
3.
4.
2
3
4
5
89%
0%
1
5%
2
5%
3
SWBAT identify and round a number to the correct number of significant figures.
4
How many significant figures?
4005
1.
2.
3.
4.
1
2
3
4
95%
0%
1
5%
2
0%
3
SWBAT identify and round a number to the correct number of significant figures.
4
How many significant figures?
nine
1.
2.
3.
4.
1
2
3
infinite
90%
10%
0%
1
2
0%
3
SWBAT identify and round a number to the correct number of significant figures.
4
How many significant figures?
200.
1.
2.
3.
4.
1
2
3
4
94%
6%
1
0%
2
0%
3
SWBAT identify and round a number to the correct number of significant figures.
4
How many significant figures?
200.0
1.
2.
3.
4.
1
2
3
4
85%
15%
0%
1
0%
2
3
SWBAT identify and round a number to the correct number of significant figures.
4
How many significant figures?
0.009009
1.
2.
3.
4.
2
4
6
7
60%
25%
10%
5%
1
2
3
SWBAT identify and round a number to the correct number of significant figures.
4
How many significant figures?
-500
1.
2.
3.
4.
1
2
3
4
74%
26%
0%
1
2
0%
3
SWBAT identify and round a number to the correct number of significant figures.
4
How many significant figures?
-500.
1.
2.
3.
4.
1
2
3
4
89%
5%
1
5%
2
0%
3
SWBAT identify and round a number to the correct number of significant figures.
4
How many significant figures?
1.3x1032
1.
2.
3.
4.
1
2
3
4
SWBAT identify and round a number to the correct number of significant figures.
How many significant figures?
1.
2.
3.
4.
A student’s extraction procedure yields
0.0105 g of caffeine.
A chemist records a mass of 0.050080 g
in an analysis.
In an experiment, a span of time is
determined to be 8.050 x 10-3 s.
Rewrite 8.050 x 10-3 so it has three
significant figures.
SWBAT identify and round a number to the correct number of significant figures.
So how do we use this new skill?
To determine how many digits to round
do after making a calculation.
 Ex 1: How many liters are equal to 34,500
milliliters?
 Ex 2: How many milligrams are equal to
3,000.0 grams?
 Ex 3: How many centimeters are equal to
12.000 meters?

SWBAT identify and round a number to the correct number of significant figures.

Complete the Sig. Fig. and Rounding
Worksheet
SWBAT identify and round a number to the correct number of significant figures.
Homework
1.
2.
Sig. Fig. and Rounding Worksheet
Lab report: Tues. (typed)
SWBAT identify and round a number to the correct number of significant figures.

The sample of gold contained
1,200,000,000,000,000,000,000,000,00
0 atoms.
How do we keep track of ALL those zeros?
 In chemistry, some numbers are HUGE!

II. Scientific Notation
(aka: Exponential Notation)
8,000,000 =
 0.00012 =
 Integer must be 1≤x<10

Positive exponent: number > 1
 Negative exponent: number < 1 (but > 0!)








4,500,000
3,950,000,000
230
230.
0.00000045
-0.002
0.00781
Copy the number and rewrite in
scientific notation
a.
b.
c.
d.
e.
f.
g.
h.
100,000
-5,000,000
450,000,000,000
1,300
0.01
0.00 005
-0.0 045
0.00 000 000 000 000 023
Remember…
A negative exponent is a tiny number but
is bigger than 0 (NOT a negative number!)
 A big exponent is a HUGE number.
 A negative number can have either a
positive exponent or a negative exponent.

Round to three sig. fig. and express in
exponential notation.
1.
2.
3.
4.
745,000
0.00054000
540,321,324
0.143589
Homework

Handout: Significant Figures and
Scientific Notation
III. Rules for Sig. Fig. in Mathematical
Operations

A. Multiplication and Division
 The number of sig. fig. in the results
should be the same as the number of sig.
fig. in the least precise measurement
used in the calculation.
 Example: 4.56 x 1.4 = 6.38  6.4

B. Addition and Subtraction
 The result should have the same number
of decimal places as the least precise
measurement used in the calculation.
 Example: 12.11 + 18.0 + 1.013 = 31.123
 31.1 (one decimal place)
13 x 1.000 = 13.000 =
 23.45 x 400 = 9380 =
 5000 / 3.12 = 1602.56410256…


14 + 3.567 = 17.567

56.2 + 23.988 = 80.188

100 – 1.9995 = 98.0005
IV. Rounding
Calculate first, then round
 Example: round 4.348 to two sig. fig.
 4.3
 Never round until your final answer!
