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Classifying Triangles and Triangle Properties

4th Grade · Math · Open Global Math

6 lessons

Goal

Classify triangles by both side lengths and angle measures, understand that triangle interior angles sum to 180°, and solve for missing angles.

6 lessons
0 of 6 done
  1. Classifying Triangles: Equilateral, Isosceles, and ScaleneUp next
  2. Classifying Triangles by Angles: Acute, Right, and ObtuseNot started yet
  3. Two-Way Triangle Classification by Sides and AnglesNot started yet
  4. The Triangle Interior Angle Sum: 180 DegreesYou are here
  5. Finding Missing Angles in Right and Isosceles TrianglesNot started yet
  6. The Triangle Inequality: Determining Possible Side LengthsNot started yet
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Learning standards covered

GlobalOGM.5.G.3Open Global Math Standards 2026™ · 4th Grade

Classify 2D figures based on angle types and side properties (triangles: acute, right, obtuse, equilateral, isosceles, scalene; sum of angles in a triangle = 180°; quadrilaterals: squares, rectangles, rhombuses, parallelograms, trapezoids; regular polygons; circles: radius, diameter, chord, center).