Third graders learn that a polygon follows clear rules, a closed shape with straight sides and no curves, and test shapes against those rules, then sort them into polygons and non-polygons.
Students will be able to…
A triangle is a polygon but a circle is not, even though both are shapes. What rules let one in and keep the other out?
Project this and sort each shape into polygon or not a polygon — tap a shape, then tap where it belongs.
Tap any phase to open the teacher moves and student actions.
A triangle is a polygon, but a circle is not. Both are shapes, so what is the rule that lets one in and keeps the other out?
Students sort shapes into polygons and non-polygons.
Students check a shape against the rules.
Students draw and sort.
Students reflect on polygons.
Aligned to the Common Core State Standards for Mathematics (Grade 3).
Understand that shapes in different categories may share attributes, such as having straight sides.
Recognize and draw shapes having specified attributes, such as a given number of sides.
Understand that attributes of a category of figures belong to all figures in that category.
Look for and make use of structure.
Preview the three formative checks. Tap “Sample answer” to see what mastery looks like — hide them before you print for students.
Have students draw two polygons and two non-polygons and label why each one belongs, so the rules become their own test. A printable polygon worksheet is in the Mathematics library.
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A quick self-check with instant feedback, drawn from this lesson’s key terms.
A print-and-go review sheet with a built-in answer key. Tap “Show answer key” to reveal answers, or print the clean version for students.