Unit 3: Fractions and Decimals

Week 8: Adding and subtracting fractions

Warning! This week looks short.  It does have less different stuff in it than last week's assignments did.  It is an illusion that this is easier.  It's not.  This topic usually takes a full week, because, after doing all this in 1-2 days, people like you usually turn in stuff, and they have missed half of the important ideas.  Then I have to stop the class and redo everything, and make everyone in the class redo everything.  I will do that to you, if you miss stuff the first time around.  Watch and read carefully, think about details, and don't get lulled into a false sense of security because it seems easy.

Resources: All of my fraction applets
A SMART Notebook with fraction circles in it! (This worked way better than I expected)
A SMART Notebook with grids for fraction squares in it, and a video showing how it works.
Instructions for explanation videos about fractions

Writing word problems

A fraction of something: multiplication and recognizing wholes
 How to specify a fractional amount for an addition or subtraction word problem
Subtraction word problems revisited
Analyzing word problems "of" and other things that might go wrong.  An analyzed exampleWord problems to analyze
Assignment: Write addition and subtraction of fractions word problems . (Warning--if you mess up your subtraction word problems, I will insist that you redo them until you get them right)
Quiz: Analyzing addition and subtraction word problems. (In D2L quizzes) Aug 5

Adding and subtracting with materials:
Watch: Examples of how to explain adding and subtracting fractions with different denominators
Adding with fraction circles
Subtracting with fraction circles
Assignment: Aug 5
Adding and subtracting with fraction circles
Instructions for explanation videos about fractions

Adding and subtracting with array pictures or materials
Addition and subtraction with drawn or folded squares showing fractions
Addition and subtraction with rectangles on grid paper showing fractions
Read: My written example of how to explain adding fractions with different denominators
Assignment: Aug 5
Write or video a detailed description of how to add fractions using an array diagram, paying special attention to how the array is formed, and how the equivalent fractions are deduced using multiplication from the array (3/8 + 4/5).
If you are not doing all this at the last minute (ie August), I recommend that you wait until you have feedback on your addition explanation, before doing..
Then, do the same thing for a subtraction .of fractions problem (7/8 - 2/3). Aug 6
(If you chose to do these as videos, you may use screen captures from the applets to make your diagrams)
Instructions for explanation videos about fractions
Adding and subtracting fractions numerically: with and without a least common denominator
Watch: 3 levels of abstraction in numerical fraction work
Examples with addition
Examples with subtraction
Choose a fraction addition or subtraction problem where the least common denominator is smaller than the denominator that you get by multiplying the two denominators, and show how compute the sum or difference in all 3 ways I showed. (Pencil and paper work is sufficient--carefully show all steps in your work). Aug 6