Transcript Lesson 3.7

Lesson 3.7
Core Focus on Decimals
& Fractions
Measuring in Inches
Warm-up
1. What units are used in the United States
to measure length or distance?
inches, feet, miles
1
1
2. Which is larger, or ?
4
2
1
2
15
7
3. Which is larger,
or ?
16
8
15
16
14
4. Simplify the fraction .
16
7
8
4
5. Simplify the fraction .
8
1
2
Lesson 3.7
Measuring in Inches
Use a customary ruler to measure
inches and fractions of an inch.
Good to Know!
In many careers it is important to know how to measure accurately
using a ruler.
 A ruler measures inches using different sized denominators.
 A foot-long ruler has 12 inches. Each inch is separated into
1
sixteenths ( 16 ) on the ruler using different sized lines, called
tick marks.
 There are sixteen equally divided spaces between every inch on
a ruler.
Explore!
Using a Customary Ruler
Step 1
Copy and complete the table below by writing each fraction in simplest form.
Step 2
How many fractions in the table above simplify to a whole number? What do you
notice about the tick mark(s) on the ruler that correspond to the measurement(s) that are
whole numbers?
Step 3
After simplifying the fractions, how many fractions have a 2 in the denominator? What
do you notice about the tick marks on the ruler that correspond to the measurements
with a 2 in the denominator?
Step 4
How many of the simplified fractions have a 4 in the denominator? What do you
notice about the tick marks on the ruler that correspond to the measurements with a 4 in
the denominator?
Step 5
How many fractions have an 8 in the denominator? What do you notice about the tick
marks on the ruler that correspond to the measurements with an 8 in the denominator?
Step 6
After simplifying the fractions, how many fractions have a 16 in the denominator?
What do you notice about the tick marks on the ruler that correspond to the
measurements with a 16 in the denominator?
Measuring with a Customary Ruler
1. Locate the tick mark that most closely
matches the length of the object.
2. Record the whole number of inches.
3. Record the fractional part of an inch that
the tick mark represents.
4. Write the whole number of inches with the
fraction part of an inch in simplest form.
Example 1
Measure the line using inches on a ruler. Measure to the nearest 16th of an inch.
a.
Line up the “0” inch mark of the ruler with the left edge of the line drawn.
Identify which mark on the ruler corresponds to the right end of the line.
2
 3 162
16
The line corresponds to 3 whole inches
plus 2 additional tick marks.
3
Write the fraction in simplest form.
3 162  3 18 inches
Example 1 Continued…
Measure the line using inches on a ruler. Measure to the nearest 16th of an inch.
b.
Line up the “0” inch mark of the ruler with the left edge of the line drawn.
Identify which mark on the ruler corresponds to the right end of the line.
The line corresponds to 2 whole inches
plus 4 additional tick marks.
Write the fraction in simplest form.
2
4
 2 164
16
2 164  2 14 inches
Example 2
Measure the line to the nearest quarter inch.
Measuring to the nearest quarter inch means the answer could include
1
2
3
4
inch,
inch,
inch, or
inch.
4
4
4
4
2
1
4
and 4
1
Notice: 4  2
1
Use a ruler to see that the line is 2 inches and then ends closer to the tick
4
1
mark than the tick mark.
2
The line is about
2 14 inches long.
Communication Prompt
What is the most difficult aspect of using inches
for measurements?
Exit Problems
1. Draw and label a line that is 1 14 inches long.
5
2. Draw and label a line that is 3 16
inches long.
3. Draw and label a line that is 2 18 inches long.
4. Measure ___________ to the nearest sixteenth of an inch
(fill in the blank with an item you have with you).