Lesson 3

Fair Shares or Not Fair Shares

Est. Class Sessions: 2
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Mathematical Standards

2.G.A
Reason with shapes and their attributes. (2.G.A.2, 2.G.A.3)

Standards for Mathematical Practice

MP1.
Make sense of problems and persevere in solving them.
MP2.
Reason quantitatively.
MP3.
Construct viable arguments and critique the reasoning of others.
MP4.
Model with mathematics.
MP5.
Use appropriate tools strategically.
MP6.
Attend to precision.
MP7.
Look for and make use of structure.

Students use models to find and describe equal shares. They learn that equal shares of the same square, rectangle, or circle do not have to be the same shape.

Content in this Lesson

  • Partitioning shapes into equal shares [E2].
  • Using words and models to describe equal shares (e.g., half, half of) [E4].
  • Recognizing that equal shares of the same whole do not have to be the same shape [E5].
  • Recognizing that the same fractional parts of different-size unit wholes are not equal [E7].
  • Finding a strategy [MPE2].
  • Checking for reasonableness [MPE3].
  • Communicating solution strategies [MPE5].
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Materials for Students

Daily Practice and Problems Lesson Homework Assessment

Student Books

 Student Activity Book

Teacher Resources

 Teacher Guide - digital

Supplies for Students

set of pattern blocks (4 yellow hexagons, 24 green triangles, 16 brown trapezoids, 12 blue rhombuses, 8 red trapezoids)
paper
scissors
one prepared paper square from Square Model Master (Teacher Guide). See Materials Preparation.
red, blue, and yellow colored pencil or crayon

Materials for the Teacher

5 prepared paper circles from Circle Model Master (Teacher Guide). See Materials Preparation.
prepared model from Unusual Cut Master (Teacher Guide). See Materials Preparation.
Unit 13 Assessment Record
Math Facts Class Record
Display set of pattern blocks (hexagons, triangles, brown trapezoids, blue rhombuses, red trapezoids)
prepared large paper square. See Materials Preparation.
gluestick
tape
scissors
crayons or colored pencils, optional

Materials Preparation

Prepare Circle Models. Make 4 copies of the Circle Model Master on white copy paper. Make one more copy of the Master on colored paper. See Figure 1. Cut the circles out.

image

Figure 1: Using 3 of the white circles and the colored one to discuss pizza models and one to show an example of "not fourths"

Prepare Square Models. Copy and cut enough of the Square Model Master so that each student has one square. Make several extra squares. Students will use these for sandwich models. Make one very large paper square to represent a giant sandwich.

Prepare the Unusual Cut Model. Make one copy of the Unusual Cut Master. Cut along the lines so that you cut the model into fourths.

Prepare Optional Targeted Practice. Make copies of the Halves and Not Halves, Fourths and Not Fourths, and Thirds and Not Thirds Masters. Place in a center with scissors and colored pencils or crayons.

Assessment in this Lesson

Assessment Expectation Assessed Math Practices Expectation Assessed
Fair Shares or Not Fair Shares
Check-In: Questions 1H
Student Activity Book
Page 655
E2. 
Partition shapes and sets into equal shares.
E4. 
Use words and models to describe equal shares (e.g., half, half of).
Fourths, Thirds, and Halves
with Feedback Box
Student Activity Book
Pages 657–658
E4. 
Use words and models to describe equal shares (e.g., half, half of).
E5. 
Recognize that equal shares of the same whole do not have to be the same shape.
E7. 
Recognize that the same fractional parts of different-size unit wholes are not equal.
MPE3. 
Check for reasonableness. I look back at my solution to see if my answer makes sense. If it does not, I try again.
MPE5. 
Show my work. I show or tell how I arrived at my answer so someone else can understand my thinking.
DPP Item K
Sharing Stickers
Teacher Guide - digital
E10. 
Demonstrate fluency with the subtraction facts related to the addition facts in Group E (11 − 1, 11 − 10, 12 − 2, 12 − 3, 12 − 4, 12 − 5, 12 − 7, 12 − 8, 12 − 9, 12 − 10, 13 − 3, 13 − 4, 13 − 5, 13 − 8, 13 − 9, 13 − 10, 14 − 5, 14 − 9).