Download Unit Conversion Lesson

Setting up Proportions:
Let’s have a closer look at our Map-area work from yesterday
Mercator:
Area of Africa in cm 2
Area of Africa in km 2
Area of North America in cm 2:
Area of North America in km 2
24.71 million km²
Wimpel-Tripel:
Area of Africa in cm 2
Area of Africa in km 2
Area of North America in cm 2:
Area of North America in km 2
24.71 million km²
*finish exit card from Tuesday
These same proportions can help us to convert between different units:
Unit Conversion Lesson
To measure the quantity of anything, we need a comparison
with some precise unit value. Early humans used body parts
and natural surroundings to provide suitable measuring
instruments.
Historical units of measurement
This derivation of the Vitruvian Man by Leonardo Da Vinci
shows nine historical units of measurement. Da Vinci drew the
Vitruvian Man to scale, so the units shown here are in their
proper historical ratios.
Rudimentary measures became essential in primitive human societies for tasks such as building
dwellings, making clothing, bartering for food and exchanging raw materials:
● Early Babylonian and Egyptian records show that length was first measured with the
forearm (cubit), hand (palm and span) and the finger (digit).
1 cubit= 444.25 mm.
a) How long is 50 cubits in mm?
1 hand span =222.12 mm
b) How long is 42 hand spans in cm?
Plant seeds were used to establish volume measure, and
with the development of scales for weighing, seeds and
stones served as standards. For example, the carob seed
was the base measure for the carat, which is still used as a
mass unit in the gemstone industry.
A carat is defined as exactly 0.20 grams.
a typical carob seed is about 0.20 grams, so 1 carat = 1 carob seed (approximately)
c) How much does a 100 carat diamond weigh in grams?
d) How many carrots does a 0.54 g diamond weigh?
Think about it….
2. Think about the following questions and discuss with your group. Complete the table.
If the unit of measure changes from
centimeters to millimeters, are more or
fewer units needed to measure the same
distance? Explain.
What measurements are usually measured
in imperial, and what measurements are
usually measured in metric?
What measurements are regularly
measured in both imperial and metric?
Different cultures use various measurement systems:
3. For example, in the Islamic tradition, a donation of charity or alms on Eid is called a Sāʿ.
Traditionally, this is the volume of grain that can be gathered in your two hands held together, four
times.
Using the info below, estimate how much
grain this is in grams.
TIME
4. Is a million seconds almost as many as a billion seconds, or not? Which is closer to the number of
seconds in a month?
5. How much greater is a millisecond than a nanosecond? Could you tell the difference if something
took a millisecond instead of a nanosecond?
AREA
6. Which rectangular community garden has the least area?
Garden A: 12.5 m × 5.8 m
Garden B: 12.5 feet × 5.8 feet
Explain why.
7. Find the length of the missing side of each of the two triangles below (NOTE: you will
need to remember how to use the THE SUM OF SQUARES. If you forget, go back and
look at that lesson).