Name: _____________________
Unit 1:2
Period: _____________________
Metric System
For everyday measuring in the United States, we use the British system of pounds,
gallons, and feet, but science (and the rest of the world) uses the easier metric system.
All measurements in the metric system are based upon the basic units of meters, liters, and grams.
Basic Units
Liters
measure
volume.
Meters measure length.
Prefixes
Grams
measure
mass.
Hard to remember
The ease of the metric system comes in its
use of prefixes. The British system uses
completely different units when changing
between small and large measurements.
The metric system simply uses prefixes.
British lengths:
12 inches = 1 foot
3 feet = 1 yard
5,280 ft = 1 mile
Easy to remember
Small
Large
Metric lengths:
10 millimeters = 1 centimeter
100 centimeters = 1 meter
1,000 meters = 1 kilometer
How to Convert using Math
Most Common Metric Prefixes
(M) Mega = 1,000,000
(k) Kilo = 1000
(c) Centi = 1/100th
(m) Milli = 1/1000th
( ) Micro = 1/1,000,000th
So, 1 Megaliter (ML) = 1,000,000 liters
So, 1 Kilogram (kg) = 1000 grams
So, 100 Centimeter (cm) = 1 meter
So, 1000 Milliliter (ml) = 1 liter
So, 1,000,000 Micrometer ( m)= 1 meter
to
75 Mm 1,000,000 m
= 75, 000, 000m
1
1 Mm
from
To convert from Mm, the units must cancel,
so Mm must be on the bottom in the ratio.
Because the metric system is based on multiples of ten, you can convert between metric
units by simply moving the decimal the correct number of places.
A Decimal System
million
Prefix Diagram:
Conversion Ratio = to 1
Base unit
thousand
hundredth thousandth
Mega- __ __ Kilo- __ __ m, L, __ Centi- Milli- __ __ Microor g
Mega– to Kilo- (Ex. 1)
To convert in the metric system,
just move the decimal.
1
1000.0
1000000.0
100000000.0
1000000000.0
1000000000000.0
megameter (Mm) =
kilometers (km) =
meters (m) =
centimeters (cm) =
millimeters (mm) =
micrometers ( m)
How Big Are They?
Micro– to Centi- (Ex. 2)
Ex. 1—Convert 34 Mm to km. Solution: Since Kilo is 3 places to the
right of Mega (see above), move the decimal 3 places to the right.
So, 34 Mm = 34,000 km.
Ex. 2—Convert 125.9 µg to cg. Solution: Since Centi- is 4 places to the
right of Micro (µ) (see above), move the decimal 4 places to the left.
So, 125.9 µg = 0.01259 cg.
It’s important to have a real-life idea of the size of these units so we are not just
talking numbers. A good scientist knows if a number makes sense.
Volume
1 liter = just bigger than a quart
1 mL = volume of a small marble
Mass
1 kg = 2.2 pounds
1 gram = 1 dollar bill
1 gram
1 quart
LENGTH
1 mm = width of a fingernail
1 cm = width of your pinky
1 meter = 3.3 ft (just bigger than a yard)
1 kilometer = 0.6 miles
1 liter
Actual size
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Copyright © 2008, C. Stephen Murray
Name: _____________________
Unit 1:2
Period: _____________________
1. Liter
A. Used by science for all measurements
2. Metric
System
B. Basic metric unit of volume.
3. Gram
C. Basic metric unit of length.
4. British
System
D. System of pounds, feet, and gallons.
5. Meter
E. Basic metric unit of mass.
11. Liter
12. Gram
13. Centimeter
14. Kilometer
15. Meter
16. Kilogram
17. Millimeter
A.
B.
C.
D.
E.
F.
G.
Just bigger than a yard: 3.3 feet.
Mass of a dollar bill
0.6 miles
Just bigger than a quart
2.2 pounds
Width of a fingernail.
Width of your pinky.
Circle the bigger unit
6. Centi-
A. Means “one hundredth” (1/100).
7. Mega-
B. Means “one million” (x 1,000,000).
8. Milli-
C. Means “one millionth.” (1/1,000,000).
9. Micro-
D. Means “one thousandth” (1/1,000).
10.Kilo-
E. Means “one thousand” (x 1,000).
Meters, Liters, or Grams?
18. To measure how much water is in a pool? _____
19. To measure the mass of an ice cream cone? _____
20. To measure the width of a table? _____
21. To measure the distance a car traveled? _____
22. To measure how much acid to pour into a beaker? _____
23. To measure how much powder to mix into water? _____
30.
31.
32.
33.
34.
35.
36.
37.
How many cents in a dollar?
How many years in a century?
How many years in a millennium?
How many centimeters in a meter?
How many millimeters in a meter?
How many microliter in a liter?
How many meters in a kilometer?
How many grams in a megagram?
24.
25.
26.
27.
28.
29.
A centimeter or a megameter?
A liter or a microliter?
A megagram or a kilogram?
A megameter or a micrometer?
A milliliter or a microliter?
A milligram or a centigram?
38.
39.
40.
41.
How does the decimal move?
42. From kilometers to meters?
Ex: From kilometers to meters? Ans: Right 3 places
43. From microliters to megaliters?
From meters to centimeters?
From centigrams to kilograms?
44. From kilograms to centigrams?
From micrometers to millimeters?
45. From liters to megaliters?
The small marks on the ruler are millimeters.
53. Convert 435 centimeters to meters.
54. Convert 12 grams to milligrams.
46. How many millimeters is the gray object?
47. How many centimeters is the object?
55. Convert 3 megameters to meters.
48. How many meters is the object?
56. Convert 0.25 centiliters to milliliters.
57. Convert 15 µm (micrometers) to centimeters.
49. How wide is the cylinder in cm?
58. Convert 4,500 meters to kilometers.
50. How wide is the cylinder in meters?
51. How long is the rectangle is millimeters?
52. How long is the rectangle in meters?
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Name: _____________________
Unit 1:3
Period: _____________________
Measuring
Science gains knowledge that must be verified through experimentation.
Good measuring allows us to collect data that can be verified.
Why We Measure
Reading The Meniscus
Before you measure read the scale to
know what each hash mark means.
Reading the Scale
Water adheres (sticks) to glass and
seems to be “climbing the sides”.
This is called the “meniscus”.
1 + 6(0.1)
Read at the
bottom of the
meniscus!
Read at eye-level
35
1mL = 10 marks
= 1 + 0.6
So, 0.1 mL per mark
= 1.6 m L
32 mL
of water
30
20 + 2(2)
Did you know?
There is no
meniscus
in plastic!
25
Reading from above
gives a high reading.
Reading from below
gives a low reading.
10mL = 5 marks
= 20 + 4
So, 2 mL per mark
= 24 m L
Balance scales are used to measure mass. Move the sliders until the scale is
“balanced”, then add together the amounts for each slider to find the total.
Balance Scales
40 grams Slider 1
+300 grams Slider 2
+1.7 grams Slider 3
341.7 grams Total mass
Make sure the scale is balanced when there is
nothing on it. If not, you will have to “zero”
it – adjust it to read zero before you use it.
Accuracy vs. Precision
Accuracy: how close a measurement is to the correct number. Ex. If 35.6 grams is the
correct mass, then 35.7 g is accurate (very close to the correct number).
Precision: how close measurements are to each other. A precise instrument will give the
same number if multiple people measure with it. Ex.: 12.11 cm; 12.12 cm; 12.10 cm are
all very close to each other, so they are precise.
Accurate
(hit the center)
Precise (all close
to the same spot),
but not accurate
(missed the center).
Recalibration:
If an instrument is precise, but not
accurate it can be recalibrated with a
known quantity. Then it will be both
precise and accurate.
After recalibration:
Precise AND Accurate!
Most good scientific
devices are able to be
recalibrated.
Precision is increased by a finer instrument.
More Precise: accurate to 0.1 cm;
Easy to measure the exact length of the object.
Not precise: only accurate to 0.5 cm;
It is hard to tell the exact length of the object.
Around 17 or 18 mm?
1
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2
3
4
Closer marks
=
More precise
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Precisely 18 mm!
1
2
3
4
Copyright © 2008, C. Stephen Murray
Name: _____________________
Unit 1:3
Period: _____________________
Find the mass from the following two balanced triple-beam balances.
What must you always do
before measuring with
a balance scale?
Slider 1 = ______
Slider 2 = ______
Which is more precise?
A beaker:
Slider 3 = ______
Total Mass = ______
or a
graduated
cylinder?
Why?
Total Mass = ______
What do we call the curvature
of water in a glass tube?
How many ml
between the two
arrows?
How much water
is in the cylinder
at the right?
Circle the correct position
to read the meniscus.
A
How much water is in this
graduated cylinder?
C
How many marks
are there between
the arrows?
Which cylinder is
more precise?
How many mL
is each mark?
Why?
B
Why does water “climb up the
sides of the glass cylinder?
How much water is in
the graduated cylinder?
Does this occur in plastic?
While hiding the bottom ruler, measure the grey object with the
top ruler to the closest millimeter. Ask three other students for
their measurements.
Your length: ______; Others: ______; ______; ______.
1cm
2cm
3cm
4cm
How long is the black object in centimeters?
1cm
2cm
3cm
4cm
Measure the grey object with the bottom ruler.
How close were the above measurements?
Which ruler is more precise?
Why?
1cm
cstephenmurray.com
2cm
How long is the black object in meters?
What is recalibration?
Why is it important that scientific instruments are able to be
recalibrated?
3cm
4cm
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Copyright © 2008, C. Stephen Murray