Classifying Triangles

Sometimes understanding the differences between triangles can get a little difficult. There are two key parts to classifying a triangle; angles and sides. The three angles we use to classify a triangle are acute, obtuse, and right. The three side classifications we use are equilateral, isosceles, and scalene. First, it is important to know what all these words mean.

Acute triangle - ALL angles are less than 90°

Obtuse triangle - One angle greater than 90° but less than 180°

Right triangle - Exactly ONE 90° angle

Equilateral triangle - ALL three sides are the same length (Congruent)

Isosceles triangle -At LEAST two sides the same length (Congruent)

Scalene triangle - ALL sides are different lengths

We created a cutout that helped us understand the classification of each triangle. We folded in the sides to create three folds. We then made several cuts to make little windows for each word. We wrote down each definition and then drew a triangle to give a visual. Doing activities like these really help ingrain the information into your brain. I think this is a wonderful activity to do with students because it is easy to understand and easy to construct.