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Eligible Content M3.B.2.1.1
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Use a ruler to measure to the nearest ½ inch or centimeter.
Did You Know?
Ancient people who did not have a uniform system of measurement used objects
such as hands
or feet to help measure the length of items. However, there
was no standard since the items
people used were different sizes. Today
we can use customary or metric units to measure
length, as well as mass, capacity
and temperature.
Check What You Know First on Customary Units
Choose one of the following words to answer the question: inch, foot, yard
| 1. The _____ is a customary unit used to measure the length of a finger. |
Use the pictures below to answer the questions.
| 2. Is the crayon less than or greater than 2 inches long? |
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| 3. What is the measurement of the crayon to the nearest inch? |
| 4. What is the measurement of the screwdriver to the nearest half inch? |
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Key Vocabulary
Linear units are used to measure length, width, height and distance.
An inch is a customary unit used to measure length.
A foot is a customary unit to measure length or distance. 1 foot = 12 inches.
A yard is a customary unit to measure length or distance. 1 yard = 3 feet.
A mile is a customary unit to measure length or distance. 1 mile = 5,280 feet.
Learn About It Now
Customary Units
When you want to know how long an object is, you measure its length. We
measure length
in U.S. customary or metric units. To measure length,
you can use a ruler, a yardstick,
a meter stick or a tape measure.
The U.S. customary units of length measurement are the inch, foot, yard and mile.
1 inch (in.)
These are some things that are approximately 1 inch in length - Diameter
of a quarter or the
length of your thumb from the first knuckle to the tip. Smaller
objects, such as a
pencil or a nail are measured in inches.
1 foot (ft.)
These are some things that are approximately 1 foot in length - Vertical side
of a sheet of notebook paper
A person’s height or the length of a room is measured in feet.
1 yard (yd.)
These are some things that are approximately 1 yard in length - Height of a
table or the length of a baseball bat.
The length of a football field or one lap around a track is measured in yards.
1 mile (mi.)
The distance you can walk in about 20 minutes is approximately 1 mile.
The distance a person travels in a car, plane or train is measure in miles.
An inch ruler is used to measure items that are 1 foot or less. A ruler
is divided into inches.
There are 12 inches in 1 foot.
How do you measure objects to the nearest inch and half inch?
Step 1: You must align the left edge of the ruler with the left edge of the object you are measuring.
Step 2: Look at the ruler and
count the number of full inches of the object shown.
The numbers for
each inch are clearly located
at the bottom of the lines. Notice that the
lines are longer for each full
inch. The length of the crayon is 3 inches.
Step 3: To measure to the nearest ½ inch, look at
the lines between each inch.
Find a line that located half way between
each number. Notice that it is longer than all
other lines except the
full inch line. Look below to see how the ruler might look.
The length
of the screwdriver is 2 ½ inches.
When marking down a distance from a ruler, mark the whole inch, followed by
a space, then the
fraction of an inch.
For example, 1 1/2, or 2 3/8.
Look at the following English or Standard Customary Rulers. Notice that
a ruler may be divided
into various fractions of an inch such as 1/4, 1/8 or
1/16. These rulers may be more difficult to read
because they are divided into
fractions.
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| A ruler marked in 4ths. Every mark is 1/4th of an inch. |
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| A ruler marked in 8ths. Every mark is 1/8th of an inch. |
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| A ruler marked in 16ths. Every mark is 1/16th of an inch. |
The center mark/line between numbers is 1/2. This
is the half-inch mark and there is only 1. The red lines on these rulers are marked at 1/2, and 1. |
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The next smallest marks/lines on a ruler are 1/4ths and there are only 2 of these. (one-fourth of an inch) The red marks on these rulers are at 1/4, 1/2, 3/4, and 1. (1/2 is the same as 2/4) |
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The third smallest marks/lines on a ruler are 1/8ths and there are 4 of these. (one-eighth of an inch) The red marks on these rulers are at 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, and 1. |
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The fourth smallest marks/lines are 1/16ths and there are eight of these. (one-sixteenth of an inch) The red marks on this ruler are at 1/16, 1/8, 3/16, 1/4, 5/16, 3/8, 7/16, 1/2, 9/16, 5/8, 11/16, 3/4, 13/16, 7/8, 15/16, and 1. |
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On the typical ruler the basic (smallest) unit of measurement is 1/16". If you count the distance between two-inch marks (one inch) you will find sixteen lines. This is because an inch is 16/16th of an inch long. Because we like to express fractional numbers in the largest unit possible we call it one inch. So it follows that if you have 8 lines, or 8/16" you have a half-inch or ½". And likewise, if you have 4 little lines, or 4/16" you have a quarter inch and so on.
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More Practice With Customary Measurement
| Measure to the nearest inch. | |||
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Check What You Know First on Metric Units
Choose one of the following words to answer the question: centimeter, decimeter, meter
| The _____ is a metric unit used to measure the width of your index finger. |
| Is the comb less than or greater than 8 centimeters long? |
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| What is the measurement of the comb to the nearest centimeter? |
| What is the measurement of the screw to the nearest centimeter? |
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Key Vocabulary
A centimeter (cm) is a metric unit used to measure length.
A millimeter (mm) is a metric unit used to measure length. 10 millimeters = 1 centimeter.
A decimeter (dm) is a metric unit to measure length. 1 decimeter = 10 centimeters.
A meter (m) is a metric unit to measure length or distance. 1 meter = 100 centimeters.
A kilometer (km) is a metric unit to measure length or distance. 1 kilometer = 1,000 meters.
Learn About It Now
Metric Units
When you want to know how long an object is, you measure its length. We
measure length in U.S.
customary or metric units. To measure length,
you can use a ruler, a yardstick, a meter stick or a
tape measure.
The metric units of length measurement are centimeter, decimeter, millimeter, meter and kilometer.
1
centimeter (cm) The width of a large paper clip or the width of your index finger is about 1 centimeter. |
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| 1 millimeter (mm) The thickness of a penny is about 1 millimeter. |
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| 1 decimeter (dm) The width of an adult’s hand is about 1 decimeter. |
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| 1 meter (m) The length of a baseball bat is about 1 meter. |
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| 1 kilometer (km) The distance you most people can walk in about 10 minutes is about 1 kilometer. |
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How do you measure objects to the nearest centimeter?
Look at the following Metric Rulers.
| On the first ruler, each centimeter is clearly marked with a number There are 2 lines with the longer line indicating each centimeter. |
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| The second ruler also shows numbered centimeters. There are 10 smaller lines that are millimeters. There are 10 millimeters in 1 centimeter. |
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Step 1: You must align the left edge of the ruler
with the left edge of the object you are measuring.
Step 2: Look at the ruler and
count the number of centimeters of the object shown.
The numbers for
each centimeter are clearly located
at the bottom of the lines. The length of the
comb is 10 centimeters. The
length of the screw is 5 centimeters.
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More Practice With Metric Measurement
Use a metric ruler to measure each object to the nearest centimeter.
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Websites to Check Out For Extra Practice
Click below to practice measuring teddy bears in one half-unit
increments. For every correct answer,
an animation will play. Scores are
given as the game is played. This is the website:
http://www.apples4theteacher.com/measure.html
Click below to practice measuring
in inches and centimeters. This is the website
http://www.funbrain.com/measure/index.html
