PowerPoint is one of the most useful tools in my bag of tricks. It allows me to show students graphic examples of whatever abstract concept I'm trying to teach them. It allows me to use pictures, sounds, music - even videos and games to get points across the dreaded adolescent apathy barrier.
One of the biggest frustrations in putting together a good slide show presentation is citing my sources. It's not that I'm in any way reluctant to show anybody where I found stuff - it's just that after I've put in a lot of work to make a slide look really schnazzy, I hate to clutter it up with bibliography information.
That's where the the notes section of a PowerPoint slide comes in.
When you are building a slide in PowerPoint, at the bottom of the page, under the actual slide, there is a window labeled "Click to add notes". This was originally designed for nervous speakers who were likely to forget what they were showing to their audience. The idea was that they would print out a hard copy of their presentation beforehand and be able to read from their notes as they proceded.
This is where I've been citing my sources. There is plenty of room to put a formal or informal citation. If anyone asks "Where did you get your information?", you can show them your source on the spot.
[Legal disclaimer: It goes without saying that I'm not a copyright lawyer - or indeed, an expert in anything - so I don't absolutely, completely, swear in court, know for a fact that this constitutes legal attribution, but I'm pretty sure that this falls into the catagory of "Good Enough For Teachers"]
All I know is that since I started doing this, I've gotten much more concientious about copywrite stuff (a technical legal term) and I feel more like I'm modeling ethical use to my students.