Occasionally, optional supplemental readings are provided. Everyone, including undergraduates, UROPs, affiliates, and visitors are welcome - provided they have done the reading. Depending on your background, collateral reading or discussion with someone familiar with the paper or the issue may be appropriate. If a particular reference is particularly helpful in understanding the paper, consider copying and distributing it, or bring a copy to the meeting. Overheads of figures or a summary of the main points may sometimes be useful.
Demonstrations are sometimes appropriate, and fun.
The presenter is a surrogate for the authors, and is expected to be able to explain all the main arguments and figures. The Discussant s job is to highlight interesting , controversial, or less obvious but important points, often agreed to beforehand. Everyone is expected to read the paper and participate in the discussion. If you're silent the whole hour, everyone will assume that you haven't done the reading. But the converse isn't necessarily so, unfortnately.