Classify triangles by sides worksheets

Name a triangle by counting how many of its three sides match: three equal is equilateral, exactly two is isosceles, none is scalene. These free printable worksheets drill that one naming.

Kid stuck on one? You don’t just get the sheet.

Classify triangles by sides
Classify triangles by sides worksheet — Equilateral, isosceles, scalene, free printable with answer key

The answer key prints on a separate page.

What's on this sheet

The standard asks children to name a triangle two independent ways, and the mixed classifying page hands both at once. This sheet takes just the side naming, so a child settles equilateral, isosceles, and scalene before the angle names are added to the mix.

Why this sheet works

All three side lengths are printed and the triangle is drawn to match them, so an isosceles triangle genuinely has two equal sides on the page and a scalene one has three different lengths. A figure that reads 8, 8, 5 while looking lopsided would teach a child to distrust the picture, which is the last thing a naming sheet should do.

How this one works

One question from this sheet, worked through a step at a time.

Name this triangle

sides:6 cm6 cm6 cm
sides:6 cm6 cm6 cm
sides:6 cm6 cm6 cm
equilateral
  1. Every triangle has TWO names — one for its angles and one for its sides — and it has both at once. This question is asking for the SIDE name, so look only at the side lengths.
  2. Count how many are the SAME, not how long they are: all three match.
  3. All three equal is EQUILATERAL.