Changed the order of the labs.
Minor wording to a problem involving an integrating factor.
Changes in the wording for the introductory modeling problems.
Added a section on variation of parameters for the 2nd order ODEs
Added a first draft for a new activity on second order DEs
Added a second part to the new worksheet.
Added an image to demonstrate the connections within the course topics.
Rearranged the activity on modeling.
Updated the modeling activity to include a problem on energy in the system.
Minor formatting changes for the 2nd order modelign activity.
Merge pull request #39 from KellyBlack/master

This is to bring the mast branch current to the final 2012 notes. This will allow us to make changes focused on 2013 for the dev branches.
Merge branch 'black_dev' of https://github.com/KellyBlack/ODE-Recitation-Activities
change the forcing term in linearModeling.tex, it was not possible for students to integrate
Merge branch 'master' of github.com:guangmingyao/ODE-Recitation-Activities
Merge pull request #17 from guangmingyao/master

I changed the forcing term in linearModeling.tex