Vectors are central to any study of physics. Once a student understands
how to approach vector prblems, they have a tool they can use to solve
physics problems for many semesters to come.
I chose to present a unit on vectors for two reasons: It comes
early in the fall so students would not be entrenched in the routines that
develop in my room every year and it is the first really challenging topic
I cover. Before vectors, students have mastered one dimensional motion,
constant circular motion, and accelerated motion. While these topics
can be difficult, they are all tied together into vectors.
Momentum is presented after vectors, cicular dynamics, force, and energy. Momentum studies can be made as hard as many other topics, but in my classes, students always express that momentum is less difficult than others they've seen. I chose to present a second unit on momentum to see how much their previous study of vectors helped them, and because I wanted to see if the nature of the material made either vectors or momentum better suited to using online materials.