Image Lesson: Triangle Exploration

By Dominic Nouwens

Today we are going to dive into a couple lessons involving how we can use triangles features and characteristics to learn more about them and the world around us. This lesson will be directed for any traditional geometry class, which occurs anywhere from 8th-10th grade. Triangles specifically are a major milestone for students to understand and contextualize, due to their usefulness in other higher order mathematics.

Lesson 1: Recognizing Triangles

In this lesson students will get the chance to view various images, and identify triangles based of of their characteristics. Students will be asked to copy triangle examples down in their notebooks, and make educated guesses regarding how the specific shapes will be named.

Student Tasks:

View all of these triangle images in the slide show. Once done, copy these into your notebook paying close attention to your shapes, making sure that each side length is of correct proportion. After this, I would like you to follow a series of tasks:

  1. Organize your triangles however you please! This could be with regard to angle measure, side length, or general look/feel of the triangle
  2. If you had to name these triangles, what would you name them? Keep in mind the side lengths and angle measures and use them to justify your naming protocol
  3. Take a closer look at all 4 of these shapes. Is there a way to create one of these shapes with the others provided? Draw examples in your notebook with lines added, intending to create triangles from other triangles.

Image Credit (In order of appearance):

Photo by Cristofer Jeschke on Unsplash

Triangle by Imam from the Noun Project

Triangle by Mochamad Frans Kurnia from the Noun Project

Triangle by Imam from the Noun Project

Scalene Triangle by Med Marki from the Noun Project

Lesson 2: Tools to compare triangles

Students will be asked to extend on knowledge built during the previous lesson to attempt to identify different triangles and terms in the example before. This lesson would also be taught to a geometry class anywhere from 8th-10th grade.

Image by Gerd Altmann from Pixabay 

Student Tasks:

View the triangle above. Your tasks are:

-Identify how many triangles are in this picture

-Name each triangle that you find, using the letters presented in the picture

-Justify your naming criteria

2 Replies to “Image Lesson: Triangle Exploration”

  1. I like that both lesson break out of the typical math lessons that I remember from my school days. Both give students a more personal entry point to consider the properties of triangles. Letting them first “name” different types, anchors the learning when the established definitions are shared.

  2. Dom,
    It is crazy how much I have learned about triangles over the years, especially in math classes. I really like the idea of giving your own name to a triangle! Though there might be a huge disconnect between what I’d name them and the official term… I also like the application of using your named triangles for lesson 2. I remember one of my teachers asking us to find the number of triangles in an image and there were like 30!

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