1. Catalyst 10/12/10
Knowing what you know about precision, answer the following questions:
Of the numbers 1100 cm vs cm
Which is more precise?
How precise is each number?
Why would you choose one or the other number?
Objectives:
Identify and convert between units of the SI System.
Determine the number of significant figures in numbers.

2. Agenda 10/12/10
Catalyst (5)
Quick Review of Procedures and behavior (10)
SI System notes & guided practice (15)
Significant figures notes and guided practice (15)
Homework:
Conversion worksheet & bring calculator tomorrow

3. New Procedures: Catalysts
Catalysts will have a grade for answers and the stamp which will be given for silently working on catalyst 2 minutes after the bell
Stampers who stamp students who are not working silently lose their points and will not stamp again
You my make up the catalyst question, but not the stamp-except for verified excused absences
Excused absences can be verified by having parents sign and put phone number in catalyst for the day

4. New Procedures: Behavior
Every warning/reminder/incidence of inappropriate behavior loses 1 point (up to 5 per day)
Every unexcused or unverified absence loses all points
Every tardy loses 2 points for the day

5. SI: Base Units length meter m mass kilogram kg time second s
Physical Quantity
Unit Name
Symbol
length
meter m
mass
kilogram kg
time
second s
temperature
Kelvin K

6. SI: Derived Units area square meter m2 volume cubic meter m3 speed
Physical Quantity
Unit Name
Symbol
area
square meter m2
volume
cubic meter m3
speed
meter per
second
m/s
weight, force
newton N
pressure
pascal Pa
energy, work
joule J

7. Unit Conversions “Staircase” Factor-Label Method Type Visual
Mathematical
What to do…
Move decimal point the same number of places as steps between unit prefixes
Multiply measurement by conversion factor, a fraction that relates the original unit and the desired unit
When to use…
Converting between different prefixes between kilo and milli
Converting between SI and non-SI units
Converting between different prefixes beyond kilo and milli

8. 1 x 10 = 10 10 X 10 = 100 10 x 100 = 1,000 The Metric System
is based on sets of 10.
1 x 10 = 10
10 X 10 = 100
10 x 100 = 1,000

9. The mnemonic: Memorize this!
Kids Have Dropped
over
Dead Converting Metrics.

10. “Staircase” Method
Draw and label this staircase every time you need to use this method, or until you can do the conversions from memory

11. You must also know…
…how to convert within the Metric System. Here’s a good device:
On your paper draw a line and add 7 tick marks:

12. Next:
Above the tick marks write the abbreviations for the King Henry pneumonic:
k h d o d c m m l g
Write the units in the middle under the “o”.

13. Let’s add the meter line:
k h d o d c m
km hm dam m dm cm mm L g

14. Let’s add the liter line:
k h d o d c m
km hm dam m dm cm mm
kL hL daL L dL cL mL g
Deca can also be dk or da

15. Let’s add the gram line:
k h d o d c m
km hm dam m dm cm mm
kl hl dal l dl cl ml
kg hg dag g dg cg mg

16. How to use this device: Look at the problem. Look at the unit
that has a number. On the device put
your pencil on that unit.
Move to new unit, counting jumps and noticing the direction of the jump.
3. Move decimal in original number the same # of spaces and in the same direction.

17. Example #1: Look at the problem. 56 cm = _____ mm
Look at the unit that has a number. 56 cm
On the device put your pencil on that unit.
k h d u d c m
km hm dam m dm cm mm

18. Example #1: Move to new unit, counting jumps and
noticing the direction of the jump!
k h d u d c m
km hm dam m dm cm mm
One jump to the right!

19. Example #1:
Move decimal in original number the same # of spaces and in the same direction.
56 cm = _____ mm
56.0.
One jump
to the right!
Move decimal one jump to the right.
Add a zero as a placeholder.

20. Example #1:
56 cm = _____ mm
56cm = 560 mm

21. Example #2: Look at the problem. 7.25 L = ____ kL
Look at the unit that has a number L
On the device put your pencil on that unit.
k h d u d c m
kl hl dal L dl cl ml

22. Example #2: Move to new unit, counting jumps and
noticing the direction of the jump!
k h d u d c m
kl hl dal L dl cl ml
Three jumps to the left!

23. .007.25 Example #2: Move decimal to the left three jumps.
(3) Move decimal in original number
the same # of spaces and in the same direction.
7.25 L = ____ kL
Three jumps
to the left!
Move decimal to the left three jumps.
Add two zeros as placeholders.

24. Example #2:
7.25 L = ____ kL
7.25 L = kL

25. Example #3: Try this problem on your own: 45,000 g = ____mg
k h d u d c m
kg hg dag g dg cg mg

26. 45,000.000. Example #3: Three jumps to the right! k h d u d c m
kg hg dag g dg cg mg
Three jumps to the right!
45,

27. Example #3:
45,000 g = 45,000,000 mg
Three jumps to the right!

28. Example #4: Try this problem on your own: 5 cm = ____ km k h d u d c m
km hm dam m dm cm mm

29. .00005. Example #4: Five jumps to the left! k h d u d c m
km hm dam m dm cm mm
Five jumps to the left!

30. Example #4:
5 cm = km
Five jumps to the left!

31. Factor-Label Method
Multiply original measurement by a conversion factor
A fraction that relates the original unit and the desired unit.
Conversion factor is always equal to 1.
Numerator and denominator should be equal measurements.
When a measurement is multiplied by a conversion factor, original units should cancel

32. Factor-Label Method: Example
Convert 6.5 km to m
First, we need to find a conversion factor that relates km and m.
We should know that 1 km and 1000 m are equivalent (there are 1000 m in 1 km)
We start with km, so km needs to cancel when we multiply. So, km needs to be in the denominator

33. Factor-Label Method: Example
Multiply original measurement by conversion factor and cancel units.

34. Factor-Label Method: Example
Convert 3.5 hours to seconds
If we don’t know how many seconds are in an hour, we’ll need more than one conversion factor in this problem

35. Examples #5-9: Solve these problems one by one on your
whiteboard using one of the methods described.
(5) 35 mm = ____ cm
(6) 14,443 L = ____ kL
(7) kg = ____ g
(8)35.4 L = ____ mL
(9)16 mm = ____ km

36. Counting Significant Figures
The Digits
Digits That Count
Example
# Sig Figs
Non-zero digits
ALL
4.337 4
Leading zeros
(zeros at the BEGINNING)
NONE 2
Captive zeros
(zeros BETWEEN digits) 7
Trailing zeros
(zeros at the END)
IF they follow a digit AND there is a decimal point
but 8900

37. Calculating With Sig Figs
Type of Problem
Example
MULTIPLICATION OR
DIVISION:
Find the number that
has the fewest sig
figs. That's how many
sig figs should be in
your answer.
3.35 x mL = mL
rounded to 15.6 mL
3.35 has only 3 Significant figures,
So that's how many should be in
the answer.
Round it off to 15.6 mL

38. Calculating With Sig Figs
ADDITION OR
SUBTRACTION:
Find the number that has
the fewest digits to the
right of the decimal point.
The answer must contain
no more digits to the
RIGHT of the decimal
point.
64.25 cm cm
= cm
rounded to cm
64.25 has only two digits to
the right of the decimal.
Drop the last digit so the
answer is cm.

39. Practice Problems
Determine how many significant figures are in each of these numbers and problems
2.03
10.00 * 2.0 /