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