In this lesson students will think about ways that physically changing a resistor will change the value of its resistance. This often functions well as an individual brainstorm and then a group/and or class discussion. Whatever list students generate (of "Things that Affect Resistance"), length of resistor, cross sectional area of resistor, and material of resistor should be on that list. These are the things students will be investigating in the lab activity today.

After the brainstorm, students will perform an investigation to actually test 2 of these. Having previously performed the conductors vs insulators investigation, they should already know that material type (~resistivity) matters in terms of resistance. Have a brief conversation with your students to let them know that while they aren't measuring that particular one in this lab, it does matter. I think it's also a good idea to tell them that resistivity is a number assigned to each material, somewhat like density. Every material has one, so if you wanted to calculate the resistance, you would just look up the value of resistivity for the material in question. This value tells the scientist how good of a conductor/insulator the material is.