In this lab, students set up a simple circuit, using a battery pack, some alligator clips, and a miniature lightbulb. (materials needed).
A gap is left in the circuit, and by placing a variety of materials in the gap, they determine if each is a conductor, an insulator, or in the case of pencil graphite, a resistor (varies, depending on the quality of pencil).
The lab is a quick simple one, aimed primarily at middle school classrooms. With some tweaking, it could likely be modified to work as a freshmen science lab.
I also have a video of the lab (same name, available in my store), where I explain the lab setup, discuss what a conductor/insulator/resistor is, then complete the lab. I use this as a lab make-up video, but it could also be used for teacher instruction.
Included, is a simple, multiple choice pre-lab.