Add more plotting and/or biology-related material

[raacampbell]

If we remove the need for writing meanTraces (issue #1) then we can focus on getting them to write code to make plots and having them go repeatedly through the process of making function files, writing them, filling them in and testing them as they go.

[DylanMuir]

I think even without meanTraces they may still not finish the entire lab in the time we spent with them. We can add more analyses (what?) with the understanding that many groups will not finish anyway.