Fraction Cover Up

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Objective

The students will be able to add and subtract fractions with unlike denominators by using visual fraction models - in a bar format.

Big Idea

Students need to concrete models be able to see the exchange of fractions with unlike denominators.

Introduction

In this lesson students play a game called Cover and Uncover.  This lesson is a step in the process of having students compare the size of fractional parts (MP3) and helps students visualize the fractional notations to the concrete pieces.  It also has students looking at equivalent fractions and students will be using fractions with numerators other than 1. 

Your students will need fraction bar manipulatives for this lesson (MP5 - using appropriate tools).  If you don't have them already made, see my lesson Creating Fraction Bars for Visual Math

Playing the Game Cover Up

20 minutes

This game can be played with two or more players.  The goal is to be the first to cover the one-whole strip with other pieces of the fraction kit.  For this lesson I started with the Cover Up Smart Notebook lesson attached – it includes a spinner.  I’ve also included information on how to create a Creating Spinners in PowerPoint and Cover Up in PowerPoint.  You can have your students create a spinner or use dice with the fractions written on them.  Here is a link to my lesson on how to create spinners. The kids had a great time doing it and it also practiced visual spatial reasoning. When students create their own tools you are covering MP5. 

Rules to Cover Up

  1. No pieces can be overlapping.
  2. Take turns rolling the cube (spinning the spinner).
  3. The fraction face up on the cube tells which size fraction piece to place on the one-whole fraction strip. 
  4. When there is only a small piece left on the one-whole to fill in you must have rolled the exact piece.

Extensions – students can do exchange for equivalent fractions.  If they have a 1/8 they may replace it with 2/16, but that takes their turn.  Let them tell you why this may be a good change or a bad one.  Once they have done this ask them to create a game with exchanging for equivalent fractions.   While students are playing this game and the extensions they will be using visual fraction models and equations to represent the problem.  The benchmark fractions are also covered in this activity.  (5.NF. A.2).  Point out to your students that 2 one-fourth pieces is 2(1/4) = 1/2.  They can write their problems down in their journal using this notation (5.NF.B.4 multiply a whole number by a fraction and 5.NF.B.5 scaling or resizing).

Playing the Game Uncover

20 minutes

This game is similar to Cover Up but there are some options for students to choose from – when playing games there are strategy games and games of luck.  Cover up is more of a game of luck than strategy.  This game introduces a little strategy.  

Have your students start with the one-whole strip covered with two 1/2 strips.  Their goal is to be the first to uncover the one-whole completely using the following rules. 

Take turns rolling the dice.You have three options on each turn:

  1. To remove a piece (only if you have the fraction on the dice).
  2. To exchange any of the pieces left for equivalent pieces (5.NF.A.1 adding and subtracting fractions with unlike denominators).
  3. To do nothing and pass the dice to the next player.
  4. You must check your partner’s trades. This will get the students talking to each other and constructing viable arguments and to critique the reasoning of others (MP3).

Student Reflection

5 minutes

The primary point of this lesson is to have students look at equivalent fractions and to have concrete experiences that relate the meaning of symbols that represent benchmark fractions.  Therefore reflection questions should be focused on this. 

I ask my students, “What did you notice about the denominators when you played this game?”  At this point students should be relating the denominators with multiplication (5.NF.B.4).  For example, the 1/4 strip is replaced with four 1/16 strips. And 16 is a multiple of 4. Students might also express this as 16 divided by 4 is 4.  If your students don’t arrive at this independently, you will need to lead them to it.  Write/draw the fractions on the board that students used to replace one of the fraction strips, such as four 1/16 strips for a 1/4 strip.  Ask if they notice any patterns with the numbers (MP8). 

The next question I ask is, “Why do you think the denominators are multiples or factors of the equivalent fraction denominators?"

Because I always focus on student collaboration, I ask a question about behavior during the lesson.  I asked my students “Was your group successful?”  I allow students to be honest but to not use names.  When a group doesn’t work well together I will hear responses such as, “My partner had a hard time staying focused.”   My response to that sort of feedback is to ask, What can you do to help your partner(s)".  Answers at this point of the year do not include "tell the teacher",because I have worked toward having my students independently solve these problems on their own. One approach they've been coached to consider is that their partner may not know what to do and be embarrassed to ask for help.