One of the first lessons in our Triangle Unit is Classifying Triangles. I handed out this vocabulary foldable and gave my students a chance to think about the definitions before we discussed them formally. Their vocabulary foldables are glued/taped into the third subject of a 3-subject spiral.
After going over the definition and a few examples, I gave them this Classifying Triangles Cut Out Activity. They always have me check their work before gluing anything down. I tell them that I don't want to reinforce their misunderstandings!