4th grade 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.
Free printable PDF worksheet, aligned to Common Core 4.G.A.2.
A new sheet every click.
The kind of problems you'll get
Circle the most specific name for each triangle.
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Circle the kind of triangle.
Answer: obtuse
- Circle the kind of triangle.
- Circle the kind of triangle.
Every print pulls a fresh set of problems at this level, so a make-up test or a second sibling never gets the same sheet.
What's on each sheet
- Fluency. Circle the most specific name for each triangle. 10 questions per page.
Every version prints on US Letter or A4, with its answer key on the last page.
How to teach this
Have your child point at the biggest angle before reading the choices, since the name lives there. Compare it to a square corner, using the corner of an index card as the tester: smaller is acute, an exact match is right, wider is obtuse. If "it looks big" comes up, redraw the same angles with longer sides and check that the name stays put.
Watch for: Kids call a triangle obtuse because it looks big. The classification is about one angle's size, not the whole triangle's. Kids skip the tick marks and eyeball the sides. Equal sides are shown by matching ticks, not by how long the sides look.
Common questions about classifying triangles
- How does my child know an angle is a right angle?
- The drawing says so: every right angle carries a small square mark in the corner. Reading that notation is part of the standard, and it beats squinting at the picture.
- What if a triangle has two small angles and one wide one?
- Every triangle has at least two acute angles, so the name comes from the biggest angle alone. Wider than a square corner makes the whole triangle obtuse, no matter how the other two look.
Related worksheets
- 5th grade classifying triangles A step harder, same skill
- 4th grade classifying angles Same grade, nearby skill
- 4th grade classifying quadrilaterals Same grade, nearby skill
- 4th grade lines of symmetry Same grade, nearby skill
- Classifying triangles, all grades The full progression
- All 4th grade math worksheets Every skill at this level
- All 4th grade worksheets Everything at this level
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Aligned to Common Core 4.G.A.2. Reviewed by the One more sheet curriculum team. Content version 123, updated July 2026.