So you're asked to give a quick talk on brewing...

So, I decided to take a night class for fun titled "The Art and Science of Beer." The class is predominantly non-brewers. The final 'project' is to give a 15~20 minute talk to the class. If you all got the opportunity to do this, what would you talk about?

First step to making a beer, having a beer! If your allowed give a sample to everybody in the class!

I would talk about the mash process. It contains a huge amount of science, and opens a lot of doors to questions. It could easily fill 15-20min. Bobby did a great job of explaining the process in his video, it took up 20min, and it only covered a part of the mash process.

Make it a BIG sample. Then it won't matter what you say.

IF not, I think I'd probably talk about hops. After all, beer drinkers are being inundated with ads touting how some breweries use ridiculous amounts of hops and such -why not give a very basic talk on what hops actually ARE (as a bonus, get some whole hops and bring them to class, let them feel them, smell them, etc) and how they are actually utilized (bittering, flavor and aroma -by early, late and dry hopping additions).
If the others aren't brewers you will certainly have an interesting talk.

1. Tell them what you are going to tell them.
2. Tell them.
3. Tell them what you told them.

Nightbiker has the right idea, take some hops, some washed yeast, water and Grain. I would get 2 row, chocolate malt, and crystal malt. They can all try a little bit of everything. You can take pictures of the process and make a power point, or just use some already available online.

have a brew up with you and go from there

15-20 minutes is barely enough time to really tell what the entire process is about. I'd give a speech on the bare basics, and supplement with some discourse on why someone would want to homebrew. Anyone attending the class will at least be interested in beer, so maybe some of them will want to brew their own if you give them the idea.

I would start with a simple recipe and print out a copy for everyone. Maybe explain the style and why you chose it.

Film or photograph myself making the beer through out the brew day (no audio if video) and explain each step, and the readers digest of the what and why. Also documenting and explaining the difference between bottling and kegging (if you're set up for kegging) and end with a sample of the batch brewed. I'm a visual learner and I would get a LOT more out of it than a lecture.

Thanks a ton everybody. I really like the idea of getting a few varieties of hops and talking about them. It'd go well with the lecture/tasting of IPAs right before the student presentations, too. Keep the ideas coming!

Presumably the class is non-brewers who are going to be undertaking this great hobby (otherwise they wouldn't be in the class) ?

I'd take Revvy's posts and read them verbatim...

No actually, I'd compile a list of newbie mistakes and advice. Things I'd have done differently when starting, etc.

Does it have to be beer related? If not, I'd tell jokes for 15 minutes.

Yikes. If it's brewing, I don't know how you could fill JUST 20 minutes. This is a speech to be given standing around a boiling kettle and it should go as long as the boil does.

Hit them with a picture of fermenting homebrew beer (and make sure it's a picture from a "Is my beer infected" thread).

Come up with a basic recipe that you can talk about/explain the science behind. Bring samples of all your ingredients to show as you talk about them. To finish up the presentation you could throw together a 5 minute time laps video of you preparing your equipment, you brewing the said recipe, and then the fermentation process. Add in your bottling/keging process if you wish and end it with a nice poured glass of your product.

i'd talk about ingredients and what is actually in beer and leave it at that - get people excited that you can take four ingredients and make 353,340 different kinds of beer including your favorite all in your kitchen.

they're there for a reason, to get excited. excite them.

What School of Awesomeness do you attend that has a class like this? Jesus.