Roots of Reason
Roots of Reason
rootsofreason.org
two questions, not one
Anchor Chart · Grade 4 · 4.G.A.2

Classifying Triangles

Sort by side lengths. Sort by angles. Every triangle gets a name from both.
1Sort by Side Lengths
equilateralthree sides alikeisoscelestwo sides alikescaleneno sides alike
Tick marks show which sides match.
2Sort by Angles
acuteall angles less than 90°rightone right angleobtuseone angle greater than 90°
The right angle is the one to look for.
3Both Names, Not One
by sidesisoscelesby anglesright
Every triangle has both names.
One name from sides, one from angles.
4Measure. Do Not Eyeball.
6 cm6 cm6.5 cmnot equilateralisosceles
This one looks even. It is not.
Read the measurements, not the picture.