Here is a list of some things that seem to me to fall into the category of good manners:

• Class starts at 10, and I will make every effort to finish on time at 10:50. Please make every effort to arrive on time. If you must be late, do not walk in front of me, behind me, over me, or through me to get to a seat.
• We have plenty of material to cover this semester, and I'll need every minute of almost every class to discuss the important aspects of the material. Please don't start packing up for your next class until I've ended the lecture. The noise is distracting. Also, you are probably missing something important when you are not paying attention.
• If you have a cell phone, please make sure that it is turned off during class.
• Go to the bathroom before class.
• Please do not carry on personal conversations during lecture. If you have a question about the lecture, please ask. You probably will be doing most everyone a favor if you do.

I want to help you learn differential equations, and that is a lot easier if you are polite and considerate.

All of the above goes for discussion section as well.