CCSS Context:
This lesson is aligned to 1GA1, which asks students to distinguish between defining attributes (exnumber of sides) and nondefining attributes (exorientation, color, etc). Students practice describing shapes in this lesson, and they explain what the shape is based on the defining attributes. They also engage in a complex task, which is one of the key shifts in the CCSS. There is not one way to sort the shapes, and students have to reason critically (MP3) to determine a rule and sort based on it.
Review:
Yesterday we talked about the names of our shapes and what we know about them. Today we are going to see how we can make different groups of shapes that are similar based on what we know about them.
I'll quickly review the shape anchor chart we created yesterday and add in "oval". We will quickly review what an oval is and list its attributes.
Connect:
Sorting helps us look at how things are the same and different. When we make different sorting rules, it helps us make connections about our shapes, which will help us when we use them to build later.
Objective:
Today your goal is to be able to create a rule and sort shapes based on the rule.
See the attached picture for the Anchor Chart!
I have a secret rule in my head that I made about my shapes. If the shape follows my rule, I'll draw it under "Follows". If it breaks my rule, I'll draw it under "breaks".
My Groups:
Follows: Circle, Oval
Breaks: Triangle, Square, Rectangle, rhombus, hexagon
It’s your job to figure out how I sorted them. We have to look at how the groups are the same. What is the same about every group? How are the 2 groups different?
Partner talk: What do you notice about these groups? How are the shapes in each group the same?
Guiding Questions:
I'll record the rule students say at the bottom of my anchor chart.
Now you are going to get a group of shape cards. It is your job to put them into groups based on a rule and your group have to figure out how you grouped them.
Partner talk: How could you put these cards into groups?
Students may struggle to come up with rule ideas. I’ll share out a few exemplars to give them a few ideas.
I’ll pass out the envelopes from yesterday that have the shape cards in them. Each partner will get a turn to sort the cards and the other partners will get a turn to guess how they were sorted. Then the partners will switch.
See Whats My Rule video for a group that is working on this activity! We followed up the activity by discussing why the rule that the little boy said did not match the groups.
Bring students back together. I'll present one rule that I heard in the same way I presented the initial rule in the opening discussion, particularly one that was tricky for the group members.
See attached anchor chart for the rule I presented to the kids!
Group A: Intervention
For students who are struggling with the vocabulary and terms we are using, I’ll give them a rule. For example, “I am sorting my shapes into 2 groups. One group has 4 sides. The other group does not have 4 sides” and then I'll have students glue down shape cards to match the rule.
Group B: Right on Track
Students cut out their shape cards and glue them down into groups. Before they glue them down, they write down the rule they are using. Students label the cards with shape names to practice using the mathematical terms for these shapes.
Group C: Extension
As an extension, this group can get 2 sets of shape cards and make 2 rules. Students label the cards with shape names to practice using the mathematical terms for these shapes.
See attached document for the shape cards we used for this activity!
I used legal sized paper for students to glue their shape cards on. It gave them plenty of space to work with!

Students share the rule they created with their partners. If time, I'll share one more rule out with the class.