Classifying triangles worksheets
Classifying triangles worksheets for fourth grade show one drawn triangle per problem with three names to circle: acute, right, or obtuse. Right angles carry a small square mark, and the deciding question is always how the biggest angle compares to a square corner.
By grade
What students need to know
A triangle gets its name from its angles or its sides. A square mark means a right angle, and matching ticks mean equal sides.
This skill runs from 4th grade through 5th grade. Pick a grade above for level-matched sentences, teaching notes, and worksheets.
Classifying triangles across the grades
4th grade
Classifying triangles worksheets for fourth grade show one drawn triangle per problem with three names to circle: acute, right, or obtuse. Right angles carry a small square mark, and the deciding question is always how the biggest angle compares to a square corner.
5th grade
Fifth grade alternates the two naming systems: half the problems classify by angles (acute, right, obtuse) and half by sides (equilateral, isosceles, scalene). One triangle can hold a name from each family, like a right isosceles triangle.
All shapes, lines & angles worksheets →
Or all math worksheets: every grade, every topic.