How to write a good definition that does not have a counterexample.
How to use a counterexample to prove a definition or conjecture incorrect.
How to use inverse trig functions to find angles in right triangles.
How to define a circle and a sphere using the word locus.
How to determine the number of handshakes possible in a group of a certain number of people.
How to determine the types of transformations, the definition of isometry, and how to say and write a transformation's new image.