I think vectors are so much easier for students to understand mathematically if they understand them graphically. I like to use this worksheet to accomplish both, using the graphical to segue into the mathematical. Something about seeing the vector arrows and their basic geometry makes it so much easier to accept the basic trigonometry of vector mathematics. This worksheet has enough problems to it that those with little to no trig background can still get a good feel for the concept and enough practice to get good at it. Further, for those who do have a trig background, the worksheet has enough variety to still keep them thinking a little bit. Given that I have students with a vast array of mathematics backgrounds in each one of physics classes, this is really important for me!
I use this worksheet in one class period, but it spans different times for different levels of students. I have 45-minute classes at my school, and some students get this finished in class with time to spare, while some get only half finished. Those who are unable to complete the assignment in class are assigned the rest of it for homework, while those who do finish are asked to assist their classmates.