March 06, 2012
Monday, March 5, 2012 - Lesson 7.5
Lesson Goal: Fraction Addition
and Subtraction
1. Unit 6 Tests if ready.
2. Review Journal pages 194-196
3. Grade Math Boxes from this Morning
4. Work through pages 198, 198 (a), 198 (b)
using manipulatives and Smart Board
5. Go over Homework - Study Link 7.5
March 06, 2012
March 06, 2012
March 06, 2012
March 06, 2012
March 06, 2012
March 06, 2012
March 06, 2012
March 06, 2012
March 06, 2012
March 06, 2012
Grade MB 7.5/p. 199
21 points
March 06, 2012
March 06, 2012
March 06, 2012
March 06, 2012
Mental Math
Write the answers to the following problems
on your scrap paper.
1/6 of 30
1/8 of 48
1/7 of 56
5/6 of 30
5/8 of 48
4/7 of 56
9/6 of 30
10/8 of 48
11/7 of 56
March 06, 2012
Math Message
If the hexagon pattern block is the whole, what
fractions are represented by the trapezoid, the
rhombus, and the triangle?
Math Message Follow-Up
=
=
=
Use a trapezoid, a rhombus, and a triangle to form a
hexagon.
move to see shapes
What number model describes what you just did?
1
__
2
+
1
__
3
+
1
__
6
=1
March 06, 2012
Modeling Fraction Sums with Pattern Blocks
Step 1: Use pattern blocks to model each fraction to be added.
Step 2: Combine the blocks to show the sum.
Step 3: Trade the blocks in the sum for the blocks of a single
type.
Step 4: Name the fraction for the sum.
2
__
6
+
1
__
6
1
__
6
+
3
__
6
1
__
3
+
1
__
3
2
__
3
+
1
__
6
1
__
3
+
5
__
6
+
1
__
2
1
__
3
March 06, 2012
Modeling Fraction Differences with Pattern Blocks
How could you use pattern blocks to solve
2
5 - __
__
3
6
?
Cover-Up Method
2
5 - __
__
= ?
6
3
Step 1: Model the fractions with pattern blocks.
2
__
3
5
__
6
Step 2: Cover up the larger fraction with the smaller.
2
5 - __
__
= ?
6
3
Step 3: The uncovered part of the larger fraction is the
difference. The uncovered part is a triangle representing
1/6.
So,
1
2
__
5 - __
__
=
6
6
3
March 06, 2012
Modeling Fraction Differences with Pattern Blocks
How could you use pattern blocks to solve
2
5 - __
__
3
6
?
Take-Away Method
2
5 - __
__
= ?
6
3
Step 1: Model the larger fraction with pattern blocks.
5
__
6
Step 2: Remove blocks representing the smaller fraction.
The smaller number, 2/3, can be represented by 2
rhombuses. Since there are no rhombuses, trade 4
triangles for 2 rhombuses. Then remove 2 rhombuses.
Trade 4 triangles for 2 rhombuses.
Take away 2 rhombuses.
Step 3: The block(s) that are left represent the
difference.
1
2
__
5 - __
__
=
6
6
3
March 06, 2012
Modeling Fraction Differences with Pattern Blocks
Use pattern blocks to solve the following problems:
1
2 - __
__
2
3
1
__
2
1 __31
-
1
__
3
5
__
6
1
2
__
__
6
3
1
1 __
2
2
- __
3
March 06, 2012
Solving Fraction Addition and Subtraction Problems
Journal p. 198
March 06, 2012