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# Previous Methods for Teaching Rounding

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by on 26 October 2013

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#### Transcript of Previous Methods for Teaching Rounding

Under the surface
Tip of the Iceberg
Previous Methods for Teaching Rounding:
Problem Solving with Fractions Using Common Core Math Practices
Rounding Using Common Core Math Practices
Now you try:
Lewis and Clark only walked ⅗ of a mile on Saturday and ⅔ of a mile on Sunday due to a blizzard. How many miles did they walk in all?
Find the digit in the place you want to round. Circle the digit.

Underline the digit to the right of the circled digit.

If the underlined digit is less than 5 , the circle digit stays the same.
If the underlined digit is 5 or greater, round up the circled digit.

Round to the nearest tenths:
1. 4 8
1.5
MP1-Make sense of a problem and persevere in solving them.

MP2-Reason abstractly and quantitatively.

MP4-Model with mathematics

MP5-Use appropriate tools strategically
Solution:
1.48 is closer on the number line to .5 than to .4.
0
1
2
.1
.2
.3
.4
.5
1.48
Why is 1.48 rounded to 1.5 when rounded to the nearest tenth? Illustrate using a number line.
Solution:
.14 is .04 away from .10 or .1,
While it is .06 away from .20 or .2.
Why is .14 rounded to .1 when rounded to the nearest tenths? Use an area model to illustrate.
Octavia used ¾ yd of blue fabric and ½ yd of gold fabric to make curtains. How much fabric did she use to make the curtains?

Make a number line and divide it into fourths.
Cut each fourth into half.
Cut each half into fourths.
Make a number line and divide it into half.
Solution:
4/8 +
6/8
=10/8 or 1 2/8
MP1-Make sense of a problem and persevere in solving them.
MP2-Reason abstractly and quantitatively.
MP4-Model with mathematics
MP5-Use appropriate tools strategically
¾
½
+
x
2
2
/
¾
=
2
4
/
+
5
4
/
=
1
1
4
/
Previous method for adding fractions-teaching algorithm.
Octavia used ¾ yd of blue fabric and ½ yd of gold fabric to make curtains. How much fabric did she use to make the curtains?
Make an area model representing ¾ and ½.
Divide the area model representing ½ into fourths.
Combine all the fourths filling in wholes.
Solution: 1 ¼
Make a number line representing 2/3
Make an area model representing 2/3
Divide the area model representing 2/3
into fifteenths.
and 3/5.
Divide the area model representing 3/5
into fifteenths.
Combine all the fifteenths filling in wholes.
Solution:
You now have an equivalent fraction.
6/8
¾
4/8
½
You now have an equivalent fraction.
Dived each third into fifths.
and 3/5.
Divide each fifth into thirds.
/15
10
/15
9
/15
10
+
/15
9
1 whole
/15
4
=
/15
19
/15
4
1
/15
4
1
/15
19
=
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