1. Description and Measurement
Chapter 2: Section 1
Description and Measurement
Measurement is a way to describe the world with numbers
Estimation is the method of making an educated guess at a measurement.
Estimation can help you make a rough measurement of an object
Estimation is useful when exact numbers are not required

2. Description and Measurement
Chapter 2: Section 1
Description and Measurement
Precision and Accuracy
Precision is a description of how close measurements are to each other and how carefully measurements are made.
Precision is the ability to remain consistent.
Accuracy compares a measurement to the real, actual, or accepted value.

3. Refer to figure 5 on page 46
How would you describe the accuracy and precision of a basketball player who makes 97 out of 100 free throws?
How would you describe the accuracy and precision of a basketball player who has 99 out of 100 free throws hit the front rim of the basket and bounce off?
How would you describe the accuracy and precision of a basketball player who makes 33 out of 100 free throws, while the others miss the basket completely?
1. Good accuracy and good precision
2. Good precision, poor accuracy
3. Poor precision, poor accuracy

4. 2.2 SI Units brainpop-measuring matter
Chapter 2: Measurement
Measurement is a description using numbers.
The SI system of units provides a worldwide standard of measurement.
2.2 SI Units
brainpop-measuring matter
SI stands for Systeme International d’Unites which is the French term for International System of Units

5. SI Units: The International System
Prefix
Multiplier
giga-
1,000,000,000
mega-
1,000,000
kilo-
1,000
hecto-
100
deka- 10
(unit) 1
deci-
0.1
centi-
0.01
milli-
0.001
micro-
nano-
One millionth of a meter is a micrometer; one thousand grams is a kilogram. What is one thousandth of a meter? (a: millimeter)

6. SI Units: The International System
The SI system is used worldwide so that everyone is measuring quantities in the same way.
SI units are related by multiples of 10
Ex: to rewrite a kilogram measurement in grams, multiply by 1000.
5.67 kg x 1000 = 5670 grams
Move decimal 3 places to the right
Recall KHDUDCM
SI stands for Systeme International d’Unites which is the French term for International System of Units.

7. SI Units: The International System
SI Base Units
Quantity
Unit
Symbol
length
meter m
Mass
kilogram kg
temperature
kelvin K
time
second s
electric current
ampere A
amount of substance
mole
mol
intensity of light
candela cd
Candela pronounced candeela

8. SI Units: The International System
LENGTH
The meter is the SI unit of length. 1 m is about the size of a baseball bat. Rooms and buildings are also measured in meters.
Smaller objects are measured in centimeters. A twenty dollar bill is cm long.
Very small objects such as blood cells, bacteria and viruses are measured in micrometers (millionths of a meter) and nanometers (billionths of a meter)
DISTANCE
Distance is measured in kilometers. The distance from New York to Los Angeles is, 4,501 km. (1 mile = km. About how many miles is a 10K race?)
Metric conversion calculator
10K is about 6.4 miles.

9. SI Units: The International System
VOLUME
The amount of space an object occupies is its volume.
The cubic meter is the SI unit of volume. (m3) Smaller volumes are measured with a cubic centimeter (c3 or cc)
To find the volume of a square or rectangular object, measure its length, width and height, then multiply them together.
A liter is a measurement of liquid volume. A cube 10 cm by 10 cm by 10 cm can hold 1000 cm3 of water which is equal to 1 liter. (L)
VOLUME BY IMMERSION
Refer to example in book on page 52, ice cubes in water.
To measure the volume of an irregular object, start with a known volume of water and immerse (or drop in) the object. The increase in the volume of water is equal to the volume of the object.
*l = 28 cm; w= 23 cm; h= 3.5 cm; v= 28 x 23 x 3.5 = 2,254 cm3

10. SI Units: The International System
MASS
The mass of an object measures the amount of matter in the object. The kilogram is the SI unit for mass. One liter of water has a mass of about 1 kg. Smaller masses are measured in grams. A large paperclip has a mass of about 1 gram.
Mass is measured with a triple-beam balance. The balance compares an object to a known mass.
Mass depends only on the amount of matter in an object.
WEIGHT
Weight is a measurement of force. Weight and mass are not the same.
Weight depends on gravity which can change depending on where the object is located. A spring scale measures how a planet’s gravitational force pulls on objects.
*What would happen to your mass and weight if you visited the moon?
* Weight would change, mass would not.

11. SI Units: The International System
TEMPERATURE
The physical property of temperature is related to how hot or cold an object is.
Temperature is a measure of the kinetic energy, or energy of motion of the particles that make up matter.
The higher the temperature, the more kinetic energy an object has.
The SI unit of temperature is kelvin but Fahrenheit and Celsius are the most common scales used on thermometers and classroom laboratories.
Kelvin starts at 0, Fahrenheit and Celsius do not.
TIME AND RATES
The SI unit of time is the second. (s) Time is also measured in hours. (h)
A rate is the amount of change in one measurement in a given amount of time.
Ex: Speed is the distance traveled in a given amount of time. Speeds are often measured in kilometers per hour (km/h)
Summary: What is the purpose of SI?

12. SI Units: The International System
Vocabulary word
Definition
SI (pg. 50)
meter (pg. 51)
volume (pg. 52)
mass (pg. 53)
kilogram (pg. 53)
weight (pg. 53)
kelvin (pg. 54)
rate (pg. 54)
*Modified hand-out

13. SI Units: The International System
Vocabulary word
Definition SI
meter
volume
mass
kilogram
weight
kelvin
rate

14. SI Units: The International System
Drawings, Tables, and Graphs (pg )
Drawings and illustrations can help people visualize complex concepts
A drawing can include details you see and those that are hidden
Photographs are an exact representation of an object at a single moment in time
Tables display information while graphs are used to summarize data.
Summary: What is the purpose of SI?