Name the Parts

10 min

Narrative

This Warm-up prompts students to compare four shapes that have been partitioned and examine the features of the shapes and the partitions. In making comparisons, students have a reason to use language precisely (MP6). The observations here prepare students to explore fractions later in the lesson and enable the teacher to hear how students describe the features that they see. During the Activity Synthesis, ask students to explain the meaning of any terms they use, such as “partition,” “whole,” “parts,” “pieces,” “equal,” and “halves.”

Launch

  • Groups of 2
  • Display the image.
  • “Pick 3 shapes that go together. Be ready to share why they go together.”
  • 1 minute: quiet think time
Teacher Instructions
  • “Discuss your thinking with your partner.”
  • 2–3 minutes: partner discussion
  • Share and record responses.

Student Task

Which 3 go together?

A
Diagram. Rectangle partitioned diagonally into 2 equal parts.

B
Diagram. Rectangle partitioned into 2 parts, one part shaded.

C
Diagram. Circle partitioned into 2 parts.

D
Diagram. Rectangle partitioned into 2 unequal parts.

Solution Steps (5)
  1. 1
    Examine shape A
    →Rectangle partitioned diagonally into 2 equal parts (halves)
  2. 2
    Examine shape B
    →Rectangle partitioned into 2 equal parts, one shaded (halves)
  3. 3
    Examine shape C
    →Circle partitioned into 2 equal parts (halves)
  4. 4
    Examine shape D
    →Rectangle partitioned into 2 UNEQUAL parts (not halves)
  5. 5
    Group by equal parts
    →A, B, C go together - all have equal parts (halves); D has unequal parts

Sample Response

Sample responses:

A, B, and C go together because:
  • They are split into halves.
  • They are split into two equal-size pieces.
A, B, and D go together because:
  • They are squares.
  • They have two pieces that make a square.
A, C, and D go together because:
  • They have 2 unshaded pieces.
B, C, and D go together because:
  • They are split with a dotted line that goes straight up and down (vertical).
Activity Synthesis (Teacher Notes)
  • “Why can’t we say that D is split into halves?” (The pieces or parts aren’t the same size. The pieces have to be equal.)
  • “Another word we can use to say something was split into pieces or parts is 'partition.' Partition means to split into parts.”
Standards
Building On
  • 2.G.3·Partition circles and rectangles into two, three, or four equal shares, describe the shares using the words halves, thirds, half of, a third of, etc., and describe the whole as two halves, three thirds, four fourths. Recognize that equal shares of identical wholes need not have the same shape.
  • 2.G.A.3·Partition circles and rectangles into two, three, or four equal shares, describe the shares using the words <em>halves</em>, <em>thirds</em>, <em>half of</em>, <em>a third of</em>, etc., and describe the whole as two halves, three thirds, four fourths. Recognize that equal shares of identical wholes need not have the same shape.
Building Toward
  • 3.G.2·Partition shapes into parts with equal areas. Express the area of each part as a unit fraction of the whole. <em>For example, partition a shape into 4 parts with equal area, and describe the area of each part as 1/4 of the area of the shape.</em>
  • 3.G.A.2·Partition shapes into parts with equal areas. Express the area of each part as a unit fraction of the whole. <span>For example, partition a shape into 4 parts with equal area, and describe the area of each part as 1/4 of the area of the shape.</span>

15 min

20 min