A triangle is a polygon. It is a closed 3-sided shape made up of straight lines. The ‘tri-’ part of the word triangle means three. A triangle has 3 sides and 3 angles. Interior angles are the angles ...

Susanna Post, the 2021 Arkansas Teacher of the Year, is getting ready for a model sailboat race. Her sailboat has triangular-shaped sails. Can you help her name and classify triangles? Rise and Shine ...