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Triangle Types

Right-Angled Triangle Investigation Purpose: Students will learn properties of triangles.

Materials: A geoboard divided into a 9 pin (3 x 3) sections, dot paper.

Triangle Types Task Card To begin, set the challenge of creating as many different right-angled triangles on a 9 pin geoboard. is the same as this, but the orientation has changed

9 pin (3 x 3)

is the same as this

Students should find different right triangles.

Some students may have difficulty finding the last right triangle because of its orientation.

Extend the investigation to 16 pin 4 x 4 geoboards. Students will need to determine whether one right triangle is different from another. Words such as congruent and similar may be introduced.

In this case, the students are trying to create non-congruent right triangles. There are nine possible right-angled triangles that may be made on a 16 pin geoboard.

Š P. Swan

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Geoboard Gems

Triangle Types - Task Cards Task Card: Triangle Types Right-Angled Triangle Investigation 16 pin (4 x 4)

How many different right triangles may be created on a 16 pin (4 x 4) geoboard?

How will you know when you have found them all?

Task Card: Triangle Types Right-Angled Triangle Investigation 25 pin (5 x 5)

How many different right triangles may be created on a 25 pin (5 x 5) geoboard?

How will you know when you have found them all?

Š P. Swan

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Geoboard Gems

Circular Geoboard Investigations Purpose: To investigate triangles and regular polygons that may be made

on a circular geoboard.

Background: A regular polygon has all sides and angles the same size. An equilateral triangle is a regular triangle, that is all sides and angles are congruent (the same size). Isosceles triangles have exactly two sides the same length. A right triangle has one right angle.

Materials: A circular geoboard and circular dot paper.

Set the challenge to make some equilateral triangles on the circular geoboard.

Next, examine the ways in which isosceles triangles may be made on a circular geoboard.

Right triangles may be created on a circular geoboard.

Geoboard Gems

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Š P. Swan