National Security Agency
Classifying Triangles
Building on young mathematicians' prior knowledge of three-sided shapes, this lesson series explores the defining characteristics of different types of triangles. Starting with a shared reading of the children's book The Greedy Triangle,...
Curated OER
Triangles
Third graders recognize geometric shapes with acute angles, make geometric shapes with acute angles on geoboards, and draw acute angles on geopaper.
Curated OER
Obtuse Angles
Third graders recognize and identify geometric shapes, work with manipulatives to reinforce understanding, and create polygons with various angles to display their knowledge of the different types of angles.