Authentic Lessons for 21st Century Learning

Measure It! Name It!

Angles and Quadrilaterals 

K20 Center, Christine Cox | Published: September 16th, 2020 by Oklahoma Young Scholars/Javits

  • Grade Level Grade Level 4th, 5th
  • Subject Subject Mathematics
  • Course Course Elementary Mathematics
  • Time Frame Time Frame 2-3 class period(s)
  • Duration More 120 minutes


Students will use protractors to discover, identify, and define angles and lines. Using vocabulary developed through this activity, students will identify different types of quadrilaterals.

Essential Question(s)

Why do we measure and name angles?



Students use a Card Sort to talk about different angles.


Students learn how to use a protractor and begin measuring angles.


Students engage in a Think-Pair-Share activity to define types of angles and lines. With their new vocabulary, students reorganize their angle sorts.


Students use their understanding of angles and lines to match quadrilateral descriptions with their pictures.


Students write a short paragraph comparing two quadrilaterals.


  • Protractors

  • Rulers

  • Angles Card Sort cards

  • Quadrilaterals and Angles Notes Page

  • Quadrilaterals Card Sort cards


Organize students into groups of two or three and pass out one set of the Angles Card Sort cards per group. Have students look at the pictures and organize the cards using whatever rules they think make sense.

As a class, discuss the different ways in which groups sorted their cards.

Introduce the essential question: "Why do we measure and name angles?"


Introduce the protractor as a tool to use to measure angles. Talk about different tools used to measure and the units used to describe those measurements. Explain that degrees are used in measuring angles and show the degree symbol.

Instruct students to use protractors to measure the Card Sort angles. Model measuring with an example angle. Be sure to demonstrate by doing the following:

  1. Line up the protractor with the angle's vertex and one of the line segments.

  2. Follow the second line segment out to the protractor's circular edge.

  3. If the line segments are too short, use the edge of the ruler to extend the lines out. (This might prompt a discussion on rays.)


Using the Quadrilaterals and Angles Notes Page, have students complete a Think-Pair-Share activity to create definitions and examples of the following terms:

  • Acute

  • Right

  • Obtuse

  • Equivalent

  • Perpendicular

  • Vertices

Ask students to reorganize their angle card sorts based on their definitions of "acute," "right," and "obtuse."


Pass out the Quadrilaterals Card Sort. Have groups label the angles for each quadrilateral image as acute, obtuse, or right. Encourage them to look for parallel lines and lines that are “equivalent” in length.

As a class, engage in an I Notice, I Wonder conversation. Encourage students to use their new vocabulary in the discussion. As part of the conversation, discuss parallel lines and add this to your definitions.

Ask students to take out the written descriptions from the Quadrilaterals Card Sort. Have them match the descriptions to the pictures.

Optional: Students can glue the pictures of the quadrilaterals next to their paired descriptions in an interactive notebook or on a sheet of paper to use as a resource.


Have students choose two quadrilaterals to compare. Using the Two-Minute Paper strategy, have them explain how the two are different and how they are the same.