This SMARTnotebook is a great tool for teaching students how to classify triangles. It designed to last for several days of teaching, and it is divided into 3 different lessons: 1) classifying triangles by angle, 2) measuring angles with a protractor, and 3) classifying triangles by side length. It's interactive and has many opportunities for students to share their thinking. Additionally, it allows students to practice sorting triangles by their properties and using a protractor. Additionally, it pushes students thinking and asks them to reflect on many questions, such as: 1) can a triangle have more than one obtuse angle, 2) does a triangle have to have at least 2 acute angles, and 3) can a triangle have more than one obtuse angle? This is a great resource to use in the classroom.