Lesson 18
Design With Fractions (optional)
Warmup: Notice and Wonder: Between 0 and 1 (10 minutes)
Narrative
The purpose of this warmup is to elicit observations about partitions in number lines of different scales. In subsequent design activities, students will partition the sides of squares and other shapes into unit fractions. That process will be iterative, with the length being partitioned changing each time. The work here familiarizes students with the reasoning they will encounter later in the lesson.
Launch
 Groups of 2
 Display the image.
 “What do you notice? What do you wonder?”
 1 minute: quiet think time
Activity
 “Discuss your thinking with your partner.”
 1 minute: partner discussion
 Share and record responses.
Student Facing
What do you notice? What do you wonder?
Student Response
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Activity Synthesis
 “How are all the number lines alike?” (They all go from 0 to 1. They have the labels 0 and 1.)
 “How are they different?” (They have different lengths.)
 “How would you partition the last number line to match the rest?” (Mark the halfway point between 0 and 1.)
 “Suppose we’d like all the number lines to be partitioned into fourths. How would you go about doing so?” (Find the halfway point between 0 and \(\frac{1}{2}\) and between \(\frac{1}{2}\) and 1.)
Activity 1: Design With $\frac{1}{2}$ (15 minutes)
Narrative
The purpose of this activity is for students to create a design using the fraction \(\frac{1}{2}\) as a constraint for length. Students partition each side of a given square into halves and mark a length of \(\frac{1}{2}\) on each side. They connect those midpoints to form another shape, partition the sides into halves again, and repeat the process to make increasingly smaller shapes. Students notice that the resulting shapes are also squares, and the squares in the pattern alternate between having vertical and horizontal sides and diagonal sides.
Advances: Conversing, Representing
Supports accessibility for: Language, SocialEmotional Functioning
Required Materials
Materials to Gather
Launch
 Groups of 2
 “Let’s create a design using the fraction \(\frac{1}{2}\).”
 “Take a minute to read the activity statement. Then, turn and talk to your partner about what you are asked to do.”
 1 minute: quiet think time
 1 minute: partner discussion
 Give each student a ruler or a straightedge.
 Provide access to extra paper, in case requested.
Activity
 “Work with your partner to complete the activity. Use a straightedge when you draw lines to connect points.”
 10 minutes: partner work time
 Monitor for different strategies and tools students use to partition the sides of the squares, such as:
 estimating or “eyeballing” the midpoint
 folding opposite sides of each square in half
 copying the side length of each square onto another paper, folding it in half, and using it to mark the midpoint of all four sides
 using a ruler to measure
Student Facing
 Here is a square. On each side, mark a point to show \(\frac{1}{2}\) of its length.
Connect each point to the point on the two sides next to it. What shape did you create?

Look at the new shape you created. On each side, mark a point to show \(\frac{1}{2}\) of its length. Connect the points again. What shape did you create?
 Repeat the steps you just did at least two more times. Make some observations about the design you just created.
Student Response
Teachers with a valid work email address can click here to register or sign in for free access to Student Response.
Activity Synthesis
 Select previously identified students to share their strategies for partitioning the sides of each shape into halves. Ask them to demonstrate their methods as needed.
 “How did you know which endpoint to use as 0 or as a starting point to mark \(\frac{1}{2}\) of the length?” (It doesn’t matter. Starting from either end gives the same point.)
 Display one or more completed drawings (showing different numbers of iterations).
 “Why do you think we all ended up with the same design?” (Each time we marked the same set of points—the middle point of each side.)
 “In the next activity, we’ll creating a design with a different fraction.”
Activity 2: Design With $\frac{1}{4}$ (25 minutes)
Narrative
The purpose of this activity is for students to create a design using the fraction \(\frac{1}{4}\) as a constraint for length. The fraction \(\frac{1}{4}\) expands the number of possible designs that could be generated.
When the fractional length to be marked on the sides of a square was \(\frac{1}{2}\), students could use either end of a side as a starting point and would mark the same point. The shape that resulted from connecting the midpoints was always a square.
When the fractional length to be marked is \(\frac{1}{4}\), the location of the point changes depending on the starting point. Consequently, the shapes that result from connecting the points may be a square, another type of quadrilateral, or may vary each time. The shapes in turn determine how many iterations can be done. (For example, if the resulting shapes are narrow parallelograms, students may only be able to do 2 or 3 rounds before further partitioning becomes unfeasible.)
If time permits, encourage students color or decorate their drawings. Some students may also enjoy the challenge of creating another design using new constraints, such as:
 starting with a square of a different size or with another shape
 using another unit fraction or a nonunit fraction to mark the length of each side
 using a different unit fraction for each iteration
Students can observe regularity in repeated reasoning (MP8) in many different ways as the new shapes they make are often smaller versions of the previous shape, but this depends heavily on how they decide to mark off \(\frac{1}{4}\) of each side.
Required Materials
Materials to Gather
Launch
 Groups of 2–4
 “Let’s now create a design using the fraction \(\frac{1}{4}\).”
 “Take a minute to read the activity statement. Then, turn and talk to your partner about how you think the drawing process will be different this time.”
 1 minute: quiet think time
 1 minute: partner discussion
 Give each student a ruler or a straightedge.
 Provide access to extra paper, in case requested.
Activity
 “Take a few minutes to work independently on the activity. Afterwards, share your drawing and your process with your group.”
 “Use a straightedge when you draw lines to connect points.”
 8–10 minutes: independent work time
 6–8 minutes: group discussion
 Monitor for different strategies and tools students use to partition the sides of the shapes.
 Also monitor for the starting point students use to identify a length of \(\frac{1}{4}\) on each side of the square. For example, they may:
 always proceed in a clockwise or counterclockwise direction
 start from the left endpoint for the horizontal sides, and start from the top endpoint for the vertical sides
 start from either end of each side and in no particular order
Student Facing
 Here is another square. On each side, mark a point to show \(\frac{1}{4}\) of its length.
Connect each point to the point on the two sides next to it. What shape did you create?

Look at the new shape you created. On each side, mark a point to show \(\frac{1}{4}\) of its length. Connect the points again. What shape did you create?

Repeat the steps you just did at least two more times. Make some observations about the design you just created.
Student Response
Teachers with a valid work email address can click here to register or sign in for free access to Student Response.
Activity Synthesis
 Select students to share their strategies for partitioning each side into fourths. Ask them to demonstrate their methods as needed.
 Invite students who created different designs to share the decisions they made along the way.
 “How did you decide which endpoint to use as a starting point for marking \(\frac{1}{4}\) of the side length?”
 “Did you mark the length the same way each time?”
 “Why do you think we ended up with different designs when the fraction is \(\frac{1}{4}\)?” (We didn’t mark off \(\frac{1}{4}\) from the same starting point or using the same order, so the locations of the points and the shapes from connecting the points were different.)
Lesson Synthesis
Lesson Synthesis
“Today we used fractions to partition the sides of geometric shapes and create designs.”
“How was partitioning the sides of a shape and marking points on them like partitioning and marking points on number lines? How was it different?”
“What did you enjoy about the process of designing with fractions? What was challenging?”