Free · Grade 4 · By angles and by sides
Working on classifying triangles? Print this sheet as it is, or change the level and questions first.
The answer key prints on a separate page.
Naming by angles asks whether the widest corner is acute, right, or obtuse. Naming by sides asks how many of the three lengths match. They are independent: a right triangle can be isosceles, and an obtuse one can be scalene, and children who have only met one naming often assume the two are the same question in different words.
The side-length sheets print all three numbers and draw the triangle to match them, so an isosceles triangle genuinely has two equal sides on the page. A figure that says 8, 8, 5 while looking scalene teaches a child to distrust the picture, which is the last thing a geometry sheet should do.