Saturday, April 6, 2013

Week 2: Ways to Add and Subtract Fractions

On Tuesday this week we discussed the different ways you can represent fractions as well as adding and subtracting fractions. 

These were the topics discussed.

Spatial Relationships are having a picture of a number including where it lies on a number line.

One/Two More/Less: If you have 5/4, what is 1/4 more/less? What is 2/4 more/less?
ex: 5/4 + 1/4 = 6/4, 5/4 - 1/4 = 4/4 = 1, 5/4 + 2/4 = 7/4, 5/4 - 2/4 = 3/4

Benchmarks of 0, 1/2, and 1... is it about or below 1/2? How far away is it from 1?

Part-Part-Whole: Knowing 3/4 can be (1/2+1/4) or (1/4+1/4+1/4)

ex: 7/5

Spatial Relationship: 
One/Two More/Less: 
7/5 + 1/5 = 8/5, 7/5 - 1/5 = 6/5, 7/5 + 2/5 = 9/5, 7/5 - 2/5 = 5/5 = 1

Benchmarks: More than 1, 1 + 2/5 = 7/5

Part-Part-Whole:
(1/5+1/5+1/5+1/5+1/5+1/5+1/5), (1+2/5), (2-3/5)


One Thursday we went over showing how to represent fractions in diagrams

Running Task: If I ran 1/3 of an hour and then walked for 1/4 of an hour, how much time would that be? What fraction of an hour is that?


They ran for 20 minutes + 15 minutes, thats 35 minutes total or 35/60 minutes.

The Clock Model


Traditional Method of Adding and Subtracting Fractions:

ex: 15 3/8 + 11 7/16

  15 3/8                 15 6/16
+ 11 7/16  ----> + 11 7/16 ----> 26 13/16

  15 3/8                15 6/16
- 11 7/16 ---->  -  11 7/16 ----> 3 15/16





2 comments:

  1. I liked how much you touched on benchmark numbers to easily identify how big or small a fraction is. In class it seemed like people struggled to quickly figure out which fraction was bigger, but you did a great job of breaking down how to compare it to whole numbers and their halves. You had a really good use of images that added to your blog.

    - Sam Gaume

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  2. I loved your pictures for the clock and hour models we learned. I would have liked to see pictures for the other explanations, but overall this was a good blog. Spacial relationships with fractions can be hard to see and with the use of your picture and explanation I think you were effectively able to explain it. Good job!

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