Lesson 1.3
Core Focus on Decimals
& Fractions
Measuring in Centimeters
Warm-Up (page 11)
1. Which is larger, 5.4 or 5.7?
2. Which is smaller, 4.8 or 4.3?
3. Write the decimal that represents the following words:
eight and five tenths.
4. Write the decimal that represents the following words:
eleven and four tenths.
Please write in the Time Tracker: Centimeters, Page 13.
Lesson 1.3
Measuring in Centimeters
I can measure and draw line segments
using centimeters.
Vocabulary
Metric System
A decimal system of measurement.
 The metric system is used in a majority of countries
around the world.
 The basic unit of length in the metric system is the meter.
Other metric units, such as millimeters, centimeters, and
kilometers, are based on the meter.
Vocabulary Continued…
Tick Marks
The metric ruler is divided up using tick marks. Tick marks are
equally divided spaces marked with a small line.
1
cm
10
1 cm
3
6 and 10 cm = 6.3 cm
 Each whole number on a metric ruler represents a centimeter (cm).
 The small tick marks between each centimeter represent
millimeters (mm).
 There are 10 millimeters in 1 centimeter. One millimeter is onetenth of a centimeter.
Example 1
Find the length of the line to the nearest tenth of a centimeter.
Line up the 0 mark on the ruler with the left edge of the line.
Identify the tick mark that represents the length of the line.
Each small tick mark represents 0.1 centimeters. Count the
number of tick marks after the last whole number to find the
number of tenths.
6
+
0.3
=
6.3 cm
WHOLE NUMBER + TENTHS = TOTAL LENGTH
The length of the line is 6.3 cm.
Example 2
Find the length of the line to the nearest half centimeter.
Line up the 0 mark on the ruler with the left edge of the line.
8.8
Identify the tick mark that represents the length of the
The line is approximately 9 centimeters long.
8.8 is closer
to 9.0
centimeters
than 8.5
line.
Communication Prompt
How is measuring with centimeters related to decimals?
Practice
• ISN page 13
Exit Problems
1. Draw and label a line that is 2.4 cm long.
2. Draw and label a line that is 9.9 cm long.
3. Draw and label a line that is 7.5 cm long.
4. Measure ___________ to the nearest centimeter
(fill in the blank with an item you have with you).
Answers Vary