The Triangle Files: Classifying by Sides and Angles

Fifth Grade Families,

Your fifth grader is becoming a triangle expert! This week, students are learning that triangles can be classified in two different ways; by their sides and by their angles.

Classified by Sides

• Scalene Triangles – No sides are equal (all different lengths)

• Isosceles Triangles – Two sides are equal

• Equilateral Triangles – All three sides are equal
  

Classified by Angles

• Acute Triangles – All angles are less than 90°

• Right Triangles – One angle is exactly 90°

• Obtuse Triangles – One angle is greater than 90°
  

The 180° Rule 🔺

Here’s an important (and amazing!) geometry rule: The three angles in any triangle always add up to exactly 180°. This rule helps students find missing angles. For example, if two angles measure 60° and 80°, we can calculate the third angle like this: 180° − 60° − 80° = 40°

Important Dates

📅 Unit 8 Exam: March 5 📄 Review materials will be sent home next week to help students prepare.

Thank you for supporting our math learning at home!

Mr. Green