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May 2013

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This is where you'll find the latest happenings, news, & ideas in math teaching

Math teaching videos
My videos at YouTube show you how to teach concepts.
How to help students with multiplication tables?

Adding and subtracting like fractions
Free lesson with a video

In the video below (also available at my Youtube channel), I explain how you can teach adding and subtracting like fractions, first using visual models, coloring the crossing out parts, and then advancing into abstract problems. I also include missing addend problems.

The lesson below also explains the same ideas. It is taken from Math Mammoth Fractions 1 book.

Fractions that have the same denominator are called like fractions. Fractions that have a different denominator are called unlike fractions. Write the answers to the pictures. Check with your teacher. + = 1 4 + 2 4 =     1 4  and  2 4  are like fractions since they have the same denominator, 4. In other words, they are the same kind of parts - fourth parts.   + =   2 9 + 4 9 =     + = 3 8 + 5 8 =     = 1

Adding the same kind of parts is easy - just add the __________________.

 
1. Write the addition sentence and the answer. Give your final answer as a mixed number if possible. Shade parts in the answer picture.

+ =     a.
+ =     c.
+ =     e.

 
2. Shade parts and write an addition sentence for each problem.

a.  Shade  5 8 .  Shade another 7 8 .
c.  Shade  6 10 .  Shade another 7 10 .
e.  Shade  6 14 .  Shade another 6 14 .

3. Fill in the missing fractions. Write your answer as a mixed number if possible.

4. Shade parts and cross out parts, and write a subtraction sentence for each problem.

a.  Shade 1 5 8 .  Cross out  7 8 .
c.  Shade 1 5 10 .  Cross out 2 10 .
e.  Shade  10 14 .  Cross out  3 14 .
g.  Shade 2 1 4 .  Cross out 1 2 4 .

5. Subtract like fractions. The principle is the same as in adding: you just subtract the numerators.

6. Make your own fraction problems! Make two different problems for each answer. 

7. Add. Write a subtraction problem for each addition. Use mixed numbers when possible.

Next lesson: equivalent fractions

The ideas in this fraction lesson are taken from Math Mammoth Fractions 1 book.

Math Mammoth Fractions 1 $4.50 A self-teaching printable worktext that teaches fractions and their operations with visual models. You don't need to just memorize fraction rules blindly - learn and understand! The book covers fractions, mixed numbers, equivalent fractions, adding and subtracting like fractions and unlike fractions, adding and subtracting mixed numbers, comparing fractions, and finding a fractional part of a group.