Note to Teachers:This lesson includes two activities. Depending upon the ability level of your students, you may accomplish the tasks in one class session. Or, you may wish to separate into two lessons.
What Can You Build With Triangles?
Begin the class by reviewing triangles. You may ask questions such as:
- What is a triangle?
- How can we classify triangles based on their sides?
- How can we classify triangles based on their angles?
- Using different quadrilaterals, how can you cut or fold paper to create triangles?
Distribute the Just Two Triangles activity sheet to each student.
Have students cut out two triangles from the activity sheet.
Use the models of the square, triangle, and parallelogram to encourage students to make various shapes. Ask them to try to make these shapes with two triangles. Have the students glue the "new" shapes onto the activity sheet.
In a whole-class discussion, encourage students to share at least one important thing that they noticed about one of the new shapes: likenesses and differences; where it could be seen
in the classroom, playground, school, or at home; and so on.
Some possible drawings for the activity sheet include:
How Do You Build Triangles?
Next, display various triangular shapes and ask, "How do you know that these shapes are triangular?" The following properties of triangles should emerge from this discussion: three sides, three corners and angles, straight rather than
curved sides.
Distribute pattern blocks to each group of two to four students. Have students explore ways to make triangles with the patterning blocks.
Alternatively, you can use the Patch Tool for pattern blocks. This is an applet version of physical pattern blocks.
Have students share solutions with each other. As a class share any common findings and anything unique that students may have discovered.
Distribute and follow directions in the How Do You Build Triangles? Activity Sheet.
Have students work in pairs to give or write directions for building one of the triangles, then see if another pair of students can build it by following the directions.
Some possible solutions for the activity sheet include:
Have students compare their drawings with those of several classmates. What do they notice?
