Fractions of a Set

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Students will be able to find a fraction of a whole set.

Big Idea

Children see fractions as partitions of one whole object first. This lesson will begin them on the "tasty" path of finding fractions in a whole set.

Whole Group Lesson

20 minutes

As students gather at the community center, I put the cover of The Hershey's Fraction Book by Jerry Pallotta on the board.  I am expecting them to say "Oh, I've read that!", or, "There are fractions on that book."

When they settle, I will introduce the book and tell them that we will be reading it to find out how we can find fractions using a set as a whole.

I read the book, but only show the illustrations on the board where I can control the image.  I want students to see the whole and then how it is partitioned into a set of "sections".  I will also make sure to suggest that even though it is snapped apart, it is still the whole candy bar.

As the book proceeds, each fraction is explained in different ways (3/12 = 1/4), so I make sure to spend time discussing this using turn and talk during the reading. 

Following the reading, I give the students a situation to solve with their partner on the board.  I show 2 red tiles and 4 blue tiles.  Students figure out how to name each color as a fraction of the whole set (six pieces). I also engage them in reasoning another fraction name.

I do this several times with different color combinations.  I expect the students to need plenty of practice with this concept.

As I began to realize this was too much of an activity for the children all at one time (see the reflection), I also start to realize there were other misconceptions that I could weave into my plan for the next day. 

This student was unable to name the blue tiles in this set correctly.  The task was to create a set of tiles that was 7/15 green, 1/3 blue, and 1/4 yellow.  Listen to how she describes the blues she has as 1/3 because she has one group of three.  I will work with her, and others, to "read the directions the fractions give us" in the coming days. 

Active Engagement

20 minutes

For independent practice, I give the students a set of story problems to reason and solve. In order to help them visualize the problem, I use the Hershey Bar as the topic of some of the story problems.

They will be:

If you have a 4 section Hershey Bar and you eat one section, what fraction did you eat? What fraction is left?  Draw and explain your thinking.

You have a 12 section Hershey Bar and you eat 3 sections. What fraction did you eat and what fraction is left?  Draw and explain your thinking.   

Imagine opening a bag of Skittles.  1/3 of the bag are red, 1/4 are yellow, 1/4 are green, and 1/6 are purple. How many are there of each color? Draw and explain your thinking.

As the students work, I confer with partnerships and insert helpful suggestions and prompts to use vocabulary.  There will be a group of students I need to work with right away, to get them started, so I keep them at the front and do the first problem with them. I also do an example similar to story 3 with them before sending them off. 

Closing and Home Practice

10 minutes

In closing, I explain to the students that they are to write their own word problems using a set for the class as homework.  

We will begin our next lesson by trying to solve some of them as a class and some we will send down to the other third grade classes to solve. Therefore, my students should know their solutions, be ready to help those that are solving if necessary, and have a good model drawn on the back so the problem solver can check their thinking.