First, a quiz on the basics of rectangles and the angles formed when a transversal intersects a pair of parallel lines. Then, moving on to the idea of how triangles are classified and how we identify corresponding pieces.
Surprisingly, a lot of students remember the different types of classification schema. It always amazes me which piece of random trivia from a class will stick with students from year to year (and conversely, which won't).
Explaining how to name triangles, and stressing why it's important was a little harder to deal with. It's one of those things that appears silly and more about math being harder than it needs to be to the students. Of course I try to use an example from the future of when this will be relevant, but many students have pre-decided that even the example is stupid, so there's no point in being good at the skill we're practicing. Actually, that last sentence describes 95% of the struggles I face as a teacher.