Songs
Numberock - Classifying Triangles
The Bazillions - "Triangular Triangles"
Videos
Math Antics - Triangles
Mr. Hardy - Exploring Triangles
Mr. Hardy - Naming and Sorting Triangles by Angles
Khan - Classifying triangles
Khan - Classifying triangles by angles
Fun with Math: How to Construct a Triangle When Given the Angles
Constructing Triangles with a Ruler and Protractor
Games
Triangle and Angle Splat!
Practice on Khan Academy
Classify triangles by both sides and angles
Constructing triangles