Grade 5 Math Module 3: Addition and Subtraction of Fractions

During this morning’s grade 5 math session, participants worked through the Module 3: Addition and Subtraction of Fractions.  The first two lessons (topic A) review grade 4 standards and the concept of equivalent fractions.  Students use paper folding activities to demonstrate equivalent fractions, which helps make the concept very concrete. They use visual modeling via arrays and number lines to help make meaningful connections and the relationships that fractions have to one another.

Topic B is where students encounter fractions with un-like denominators.  They know the language of 1 apple +1 apple, 1 third + 1 third, so when they encounter 1 third +1 half, they know the units are not the same and that they need to make the units the same (common units).  Lots of work with arrays is involved here and there are some struggles, but overall the visual model helps the transition from concrete to abstract.

The group spent a lot of time on a two-step word problem from Lesson 7 that involved subtracting from a whole with uncommon units.  The solution was presented two different ways using visual models (arrays).

For topic C, participants took a look at three student solutions to the problem 3 3/5 – 2 ½.  It was interesting and exciting to see students use unbundling and decomposition that they saw in previous grades with whole numbers, and applying those concepts to their work automatically with fractions.

Topic D focuses on the problem-solving practice and application of the concepts learned. Multi-step problems are tackled with various strategies. The module does a nice job of showing the progression of equivalent fractions, making units pictorially, making units numerically, and then being able to apply knowledge to solve problems that involve addition and subtraction of unlike fractional units.


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