Triangles, Triangles, Triangles

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SWBAT identify ways to create a triangle using different combinations of shape blocks.

Big Idea

Students explore different combinations of shapes that can create a larger triangle. Students explore the idea of equivalency-which shapes can I use to replace a larger shape?

Setting up the Learning

5 minutes

CCSS Context:

In this lesson, students work on an incredibly important shape in geometry-the triangle. This lesson has students think about different ways to create composite triangles in a variety of ways, which is aligned to 1.G.A2. Through the process of practicing how to make the triangle, they also practice making other composite shapes, particularly the trapezoid and rhombus. This is a complex task, as it asks for students to show more than one correct answer. One of the key shifts in the CCSS is an emphasis on high quality, complex tasks at all grade levels.


We have been learning about shapes and thinking about how they fit together. Today we are going to think about one of the most important shapes: the triangle.


Triangles are very important because they are one of the strongest shapes. When engineers design bridges, they often use triangles because they are so strong.

I'll have students look carefully of this bridge image to see if they can find the triangles.

Objective:  Your thinking job is: How can I build a triangle using other shapes?

Student Share

15 minutes

Student Work Time:

This will probably take some time! If students find one way, see if they can find a different way to make a triangle or push them to try to record how they did it.

Bring students back together after 10(ish) minutes of work time for a share out.

Student Share: Call on students to explain the different ways they made the shape.

Technology Connection: I am using the online Illuminations tool so kids can see how other students built the hexagon.

To push students to use visualization to put these shapes together, I'll show all of the shapes a child used to make a triangle without actually putting them together yet.

Partner Talk: Try to predict how they used these shapes to put it together.

I'll show how the student put the shapes together. Then I'll model representing it on the triangle anchor chart and write words to explain what shapes to use (I used 1 triangle, 1 rhombus and 2 trapezoids).

I'll follow this same routine for a few other ways of representing.

Independent Practice

15 minutes

I used the template provided by the website It is available as a free pdf on their website! Go here to get this great resource!

Students work to find as many ways as possible to build a triangle. See attached picture for one student's work! Ways to Make Triangles

Extension: Students work off the template and make a triangle without picture support.


10 minutes

Students come together and we add to our chart about ways to make triangles.