Todd,
Thanks for your reply.
I am planning to do something similar. Then kids draw a rectangular line on
thick paper, measure resistance and length. After the first lab determines
resistivity, students should be able to determine the thickness of the
drawn "line". Pretty cool. Not my idea. I got it from a general atomics
presentation and lines if resistance material.
I believe the softer lead is better because it will go into the thickness
of the paper a bit better.
We will see.
Have a good one.
Paul.