January 12, 2010

Fractions

Why do teachers struggle teaching fractions?

• They are very abstract
• They change appearance.   For example, 1/2 can be 4/8 or 9/ 18
• Lots of steps to remember
• Parents feel helpless when it comes to helping student with fractions
• There is a cultural fear or phobia of fractions

Equivalent Fractions

• Why? 
• Why is 3/2 equivalent to 9/6? These fractions represent the same amount.  If we divided 3 by 2, the answer is 1.5. Same for 9 divided by 6.

Simplifying Fractions

• Cake Method - helps students simply fractions

Example of simplifying using the cake method.

It is a good idea to mix in improper fractions with the other fractions.  That way there is one rule instead of students thinking there are two rules to remember.

Adding Fractions

• If students can count, they can add fractions.
• Drawing models
• 2/3 + 4/5 = 
• 7/4 + 1/3 = 25/12



draw model for 7/4 and 1/3



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Adding Fractions Using the Area Model - practice problems.

Subtracting Fractions

• The model is the same as what we did for adding subtractions.  The difference is, rather than counting the number of squares that are shaded, you cancel out boxes, and then count what shaded box which is last.



Subtracting Fractions  Using the Area Model - practice worksheet

When teaching adding and subtracting fractions, start with using the area models.  Teach them separate.  Then, teach adding and subtracting together.  

• Mixed Practice - Draw the area model AND then rewrite the problem based on the new model.

Adding and Subtracting Fractions - Developing the Algorithm

Homework

• Beckman Hardcover - pg 130 #s 1, 2, 3, 4, 16. 17
• Van de Wall 342-345