Comparing Cake Slices

  • Third Grade
  • Math
  • 65 minutes
  • Standards: 3.NF.A.3
  • 4.0 based on 1 rating
August 3, 2015
by Dee Mulhern

Sweet fractions! Teach your students to compare fractions with this sweet lesson using slices of cake.

Learning Objectives

Students will be able to compare models of different fractions with denominators of 2 and 4 to determine value.

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Lesson

Introduction (5 minutes)

  • Gather students together. Engage the students with a story about being very hungry for dessert and having to choose a slice from one of two cakes. Tell your students that one piece of cake came from a cake sliced into four pieces and the other from a cake sliced into two pieces.
  • Show students a visual of the two cakes. Discuss with students how both whole cakes are the same size.
  • Tell the students that in order for you to choose a slice, you need to look at each piece as a fraction. Divide the cakes into halves and fourths.

Explicit Instruction/Teacher Modeling (15 minutes)

  • Hold up a picture of both slices. Write ¼ and 1/2 under each slice.
  • Tell students to take notice of the denominators and size of each slice.
  • Facilitate a discussion about how a greater denominator does not necessarily mean a larger part. Discuss which slice is greater. For example, discuss why 2/4 is not bigger than 1/1.
  • Give another example, this time comparing 2/4 to 2/2. Discuss with students the value of each fraction compared to each other and the cake as a whole.

Guided Practice/Interactive Modeling (15 minutes)

  • Distribute the Cake Mania worksheet. Have students cut out the ice cream cake and rainbow cake pieces.
  • Have students compare 1/2 of the ice cream cake to ¾ of the rainbow cake.
  • Ask your students to share with a partner to choose and write the greater than or less than signs to compare 2/4 to ¾.
  • Practice with more examples.

Independent Working Time (15 minutes)

  • Distribute the Comparing Fractions worksheet. Complete the first example with the students. Relate models to the cake pieces that the students previously used.
  • Have students work in pairs to complete the worksheet.

Extend

Differentiation

  • Enrichment: Have students design their own cakes and compare fractions to match. Encourage students to find equivalent fractions.
  • Support: For a student in need of extra support, have the student place the slices on a blank outline of a whole cake for each fraction.

Review

Assessment (10 minutes)

  • Collect and analyze student work to check for mastery.
  • Circulate while students work.
  • Use whiteboards at the end of the lesson to have students draw the correct symbols to compare two fractions.

Review and Closing (5 minutes)

  • Gather the students back together. Facilitate a discussion about the work they completed. Focus on discussing how to prove that the comparisons are accurate using models.
  • Go through a few more examples with students. Have students hold up whiteboards to display their answers.

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