Measurement in Inches and Centimeters

Grade 2 · Math · Study Guide

Learn how to measure objects using a ruler with inches and centimeters.

Measurement helps us find out how long, tall, or wide something is. We use tools like rulers to measure.

In the United States, we often use inches. An inch is a unit of length. There are 12 inches in one foot. On a ruler, inches are usually marked with longer lines. A standard crayon is about 3 inches long.

Centimeters are another unit of measurement used in science and in many countries around the world. Centimeters are smaller than inches. There are about 2.54 centimeters in one inch. There are 100 centimeters in one meter. A centimeter is about as wide as your pinky fingernail!

To measure with a ruler, you always start at the zero end (not the end of the ruler itself). Line up the zero mark with one end of the object. Read the number at the other end of the object. That is your measurement.

If you are measuring in inches, look at the inch marks. If measuring in centimeters, look at the centimeter marks. Many rulers show both at the same time — inches on one side and centimeters on the other.

Key terms

Inch
A unit of length in the US customary system; there are 12 inches in a foot
Centimeter
A metric unit of length; there are 100 centimeters in a meter
Ruler
A flat measuring tool with inch and centimeter markings
Length
How long or short something is from one end to the other
Estimate
A careful guess about a measurement before you measure exactly
Zero mark
The starting point on a ruler from which you begin measuring

Flashcards

Inch abbreviation
in.
Centimeter abbreviation
cm
Inches in a foot
12 inches
Centimeters in a meter
100 centimeters
Which is bigger: 1 inch or 1 cm?
1 inch (about 2.54 cm)
Where to start measuring
At the zero mark on the ruler
What tool do we use to measure length?
A ruler
About how long is a new crayon?
About 3 inches or about 7-8 centimeters

Questions

  1. Where do you start when measuring an object with a ruler?

    1. At the number 1
    2. At the end of the ruler
    3. At the zero mark
    4. In the middle
    Show answer

    Answer: At the zero mark

    You always start at the zero mark, not the edge of the ruler.

  2. Centimeters are larger than inches.

    Show answer

    Answer: False

    Centimeters are smaller than inches. There are about 2.54 cm in 1 inch.

  3. There are ___ centimeters in 1 meter.

    Show answer

    Answer: 100

    The prefix 'centi' means one hundredth, so there are 100 centimeters in one meter.

  4. A pencil measures 7 inches. About how many centimeters is that? (Hint: 1 inch is about 2.5 cm)

    1. About 14 cm
    2. About 17 cm
    3. About 10 cm
    4. About 7 cm
    Show answer

    Answer: About 17 cm

    7 x 2.5 = 17.5, so about 17 cm. The closest answer is about 17 cm.

  5. There are 12 inches in one foot.

    Show answer

    Answer: True

    This is a standard fact: 1 foot = 12 inches.

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