Typically a poster is a large document that highlights the main results of your work in a way that is easily visible from a distance/at a glance. I have asked you to produce posters because it will be quicker and easier for everyone to hear about the work you did than if we try to do powerpoint presentations, given the limited time available in class.
For those of you not familiar with posters, they are typically printed in the large and then attached to posterboard which you can buy at most art stores, or if there is enough wall space they can be taped up to the wall. Please come to class early enough to set up if you are taping yours to the wall. Here is a nice post explaining how to make posters for an academic context and another one on designing academic posters that also has examples in it.
In terms of mechanics, the SCS poster printing help page has some advice, and also tells you how to get it printed if you are part of SCS.
If you are not an SCS student, you can still print your poster through the fedex on campus but that could get expensive. A much less expensive option is to print multiple 8x11 sheets and tape them up or pin them to a single poster board (please remember to plan time for assembly in this case). Some suggestions for how to do this, according to meta filter:
Download the trial of Adobe Acrobat, import your poster
Go to print it, and set options as follows:
Print Range: Current Page
Copies: 1
Page Scaling: Tile all pages
Tile Scale: 450% (this will make an 8x11 sheet around 43 x 55)
And the rest play around with, you'll get the idea.