Geometry and Ledger Art

by Avis Prentice and AnnMaria De Mars

📖 Standards

Draw (freehand, with ruler and protractor, and with technology) geometric shapes with given conditions. Focus on constructing triangles from three measures of angles or sides, noticing when the conditions determine a unique triangle, more than one triangle, or no triangle.

⏰ Time

90-120 minutes, including time students spend on creating shapes, measurement and creating winter count artwork

📲 Technology Required

A computer with project/ smart board for viewing as a class or computer or mobile device for viewing videos at home is required. Art project can be done on Google Slides or PowerPoint or with markers and paper or construction paper, glue and scissors. Paper bags (optionally) can be used to simulate a hide background.

📃 Summary

Students begin by watching two videos that appear to be unrelated – on Native American ledger art and using a protractor to measure angles. These are explained in the presentation, that art can take many forms. Vocabulary and basic facts regarding angles are introduced. Students use an online app to create angles with different lengths of lines. After measuring lengths and angles of their shapes, students create artwork for their own event and a classroom ‘winter count’. Use of angles in computer animated art is explained. The session ends with assessment of students’ knowledge of measurement of angles.

📚 Lesson

Watch video on Native American Ledger Art

Watch to 5:07

Students will watch the video to the point of 5:07 , where the curator says to think of an event you really want to remember.

Watch video on using a protractor

Explain basic concepts and vocabulary of measuring angles

This 31-slide deck explains degrees as a measure of rotation, defines acute, obtuse and right angles and obtuse, acute and right triangles. Instructions are given for students creating their own ledger art. Available as Google slides here or as a PowerPoint Presentation here.

Students use an online app to create triangles from different lengths of lines.

Example from the GeoGebra app

In this exploratory activity, students should learn that a triangle cannot be created from any three lines. They will also get practice creating different angles and seeing the shapes of triangles with different angles. This activity is recommended but can be skipped if students do not have access to devices. Alternatively, the teacher or a student can create angles with result shown on a smart board/ projector.

Students create and measure shapes

As instructed in the presentation, students create lines, triangle and circles. They measure the diameter or radius of circles, length of lines and angles of triangles. Students write a description of their shapes using mathematical terms.

Students create their own artwork to commemorate an event

Students will use the shapes created in the previous activity to create original work. They will present their artwork to the class and explain its meaning.

Students watch a video on winter count

Emil Her Many Horses explains the creation and meaning of the winter count

Students combine their events to form a classroom record

Individual student events can be combined on poster board, included in a single Slides or PowerPoint document. Dr. Vivian Young recommends using large brown paper bags to simulate hides, crumpling and tearing around the edges to give more of a hide appearance.

End with presentation

Finish the slide presentation by informing students that their measurements are the first step a software developer would take in turning their artwork into computer animation for a game or website. They have been programming and did not even know it!


An assessment of students’ knowledge of measurement of angles and types of triangles is included here as :

Google doc file for assessment

PDF version of assessment


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