February 03, 2015
Lesson 5.2: Using Other Models to Add Fractions
Focus: Use fraction strips and number lines to add fractions.
Get Started:
Look at this picture:
1. Which fractional part can you identify immediately?
2. How can you visually rearrange the grid-square shape to more
easily name its fractional part?
3. What fractional part of the square is each other shape?
4. Why do you not automatically recognize these fractions in this
square?
February 03, 2015
A Review of Equivalent Fractions:
Equivalent Fractions:
Ex)
Ex)
- Fractions are determined to be equivalent by multiplying the
numerator and denominator of one fraction by the same number.
Ex)
Explore: p. 181
You will get a copy of this map. The map shows a section of land owned by
6 people (as shown below).
February 03, 2015
1. What fraction of land did each person own?
Smith:
Scullion:
Perry:
Haynes:
Ferri:
Chan:
2. What strategies did you use to find out?
Explore: cont....
3 people sold land to three other people.
-> Use the clues below to draw a new map.
Write addition equations such as 1/2 + 1/4 = 3/4
NEW MAP
February 03, 2015
Explore: cont....
1. Which people sold all their land?
2. What fraction of land did Smith buy? How do you know?
3. Who could Smith have bought land from? How do you know?
4. How much land did Perry sell? How do you know?
5. How much land did Chan buy? How do you know?
Explore: cont....
6. Who could Chan have bought land from? How do you know?
7. How much land does Haynes buy? How do you know?
8. Who could Haynes have bought land from? How do you know?
February 03, 2015
Fraction Strips:
Let's model some fractions with strips of paper called fraction
strips.
4/10
3/5
To add fractions with different denominators, such as 1/4 + 1/2, align the strips for
1/4 and 1/2.
Find the single strip that has the same length as the two strips.
1/2
1/4
There are 2 single strips; 6/8 and 3/4
6/8
3/4
So, 1/4 + 1/2 = 6/8
and
Simplest Form
1/4 + 1/2 = 3/4
CUT OUT YOUR FRACTION STRIPS GIVEN TO YOU AND TAPE THE
APPROPRIATE SECTIONS TOGETHER (2 pages)
Example:
1. Add 1/2 + 4/5 using fraction strips.
STEP 1: Place both strips on:
1) Halves line
2) Fifths line
STEP 2: Find a line on which to place both strips so the end of the 4/5 strip lines
up with a fraction.
STEP 3: The end of the 4/5 strip lines up with a fraction on the _____________.
The strip ends at _____
So:
February 03, 2015
Example:
2. List all fractions equivalent to (USING FRACTION STRIPS)
(See p. 183)
a) 1/2
b) 1/4
c) 2/3
Homework:
p. 184 # 2, 4ab, 5ab, 7b, 8, 9