standard_description: Understand subtraction as an unknown-addend problem. For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.
problem_activity: Narrative
The purpose of this activity is to introduce the language of
a half of
and
a fourth of
a
shape. Students begin by applying the language of halves and fourths, or quarters, to partition each shape. Students are asked to describe “how much” of each shape is shaded to elicit a variety of responses that include half, fourth, or quarter, including the phrases “of the square” or “of the circle.” Monitor for a variety of words and phrases to share in the synthesis including:
phrases that reference the pieces only (“one piece”).
phrases that reference that some, but not all of the shape is shaded (“part of it,” “a little bit”)
phrases that name the pieces (“a half,” “a fourth,” “a quarter”)
phrases that name the pieces in reference to the whole shape (“a half of the square,” “a fourth of the circle”)
All responses should be shared and compared in the synthesis to help build students understanding of the new vocabulary and the concept of fractional pieces of a whole (MP6).
Required Materials
Materials to Gather
Colored pencils or crayons
Launch
Groups of 2
Give students access to colored pencils or crayons.
Activity
Read the task statement.
2 minutes: independent work time.
2 minutes: partner discussion
Monitor for a range of ways to describe the amount shaded such as “some is shaded,” “one piece of the square is shaded,” “one out of two pieces is shaded,” or “a half is shaded.”
Student Facing
Split the square into halves.
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Color in one of the halves.
How much of the square is colored in?
Split the circle into fourths.
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Color in one of the fourths.
How much of the circle is colored in?
Student Response
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Activity Synthesis
Invite previously identified students to share for each problem. Sequence the students in the order described in the narrative.
“One piece of a shape split into two pieces that are the same size is called
a half
. One piece of a shape split into four pieces that are the same size is called
a fourth
.”
For each shape, invite students to describe how much is colored in. (A half of the square is colored in. A fourth of the circle is colored in.)


aligns: no