Date _______
Essential Question: How can fractions with different-sized fractional parts describe the samesized region?
Lesson Seed
CCSS: 3.G.2
Objective: I can partition shapes into equal parts by using a Geo-board/paper in order to express
the area of each part as a unit fraction of the whole.
Standard(s) for Mathematical Practice:
 Attend to precision- Can I create equal parts?
 Construct viable arguments and critique the reasoning of others- Can I prove why the figure is equally partitioned?
 Model with mathematics. – Can I equally partition the figures to show unit fractions?
Assessment:
Kendall said, “This is ¼ of the Hershey Bar.”
Arryn said, “This is ¼ of the Hershey Bar.”
Summer said, “This is ¼ of the Hershey Bar.”
Who is correct? ____
Use the model, drawings, words, and/or numbers to explain your thinking.
Warm-Up:
Give students a set of construction paper squares. (Need to precut squares.) Students will
independently partition the square in half or two equal parts as many ways as they can.
- Put students into groups of about 3 students and glue a variety of models that represent ½ on
a piece of chart paper. Tell students to use the models, words, and/or numbers to prove their
thinking.
- Provide time for students to share the different models.
Task:
- Give each student a geo-board with geo-bands. Tell students to put a geo- band around the
perimeter of the board to create a square. Tell students to use other geo- bands to divide the
square into four equal sized parts. Have all students hold up their geo-board to show the
teacher how they partitioned the shape. *When students share their model, ask them to turn
the geo board to show rotating doesn’t affect the shares. If they created four equal shares,
they still have four equal shares.
- Then have the students share their model with the group. If all the models are the same, ask
students to revise the models so each one looks different, but still represents fourths. Have an
additional geo-board for each group so that they can come up with an additional model if there is
time.
- Tell the students to individually record the models of the group on the geo-paper.
- Display drawn model on doc-cam and ask “How do you know these all are equally partitioned?”
Students share thinking. Teacher can record phrases/words that precisely communicate thinking
on a piece of chart paper labelled “Communicating Precisely”.
- Teacher says, “Because you have four equal parts, we say that your figure is divided or
partitioned into fourths. One of these parts is called one fourth because we are talking about
one of the fourths.”
- Record thinking on a chart, visible for all students to view, like the one below.
Number of Equal Parts
4
Name for part
one fourth, ¼
- Repeat the process above with the geo-board and 8 equal sized parts. Add the information
about 8 parts to the chart above, as well as words/phrases used to prove thinking to the
“Communicating Precisely” chart.
- Students work with a partner to complete the assessment activity (see next page) and share
answers. As students are working, make note of the use of the SMPs (see note taking sheet):
 Attend to precision- Can I create equal parts?
 Construct viable arguments and critique the reasoning of others- Can I prove why the figure is equally partitioned?
 Model with mathematics. – Can I equally partition the figures to show unit fractions ?
Closure:
“Take a moment and look at the halves, fourths, and eights you modeled. What do you notice?”
Record student thinking.
- If students do not mention that there can be more than one way to equally partition a whole
into different parts, add the statement to the list.
Date _________________________
Evidence of Student Use of the Practices
 Attend to precision- Can I create equal parts?
 Model with mathematics – Can I equally partition the figures to show unit fractions?
 Construct viable arguments and critique the reasoning of others- Can I prove why the figure is equally partitioned?
Name ______________________________ Date _________________
Who Is Correct?
Kendall said, “This is ¼ of the Hershey Bar.”
Arryn said, “This is ¼ of the Hershey Bar.”
Summer said, “This is ¼ of the Hershey Bar.”
Who is correct? ______________
Use the model, drawings, words, and/or numbers to explain your thinking.
Kendall’s Candy Bar
Arryn’s Candy Bar
Summer’s Candy Bar