For All 200 Level Physics Labs

 

Gather your material

In preparation for putting your oral presentation together, you and your partner need to spend about 10 - 15 minutes deciding what information you have that is suitable to show. Of course, most of this will come from your written report, but it need not. You may decide to supplement that information with information from the news or movies as you happen to notice places where the principles of physics you have been studying are applied. You may want to show a picture of your cat cutting flips in a discussion of angular momentum. Be creative.

The key ingredients in any oral presentation are graphs of the data and an explanation of the physics and your analysis. At a minimum you must be prepared to discuss these main points.

 

Organize your material

Once you have gathered all the bits you need, you need to organize them into a sensible order. This is done by following the two general sets of rules for oral presentation preparation.

Rule set #1 (Strategy)

1. Begin your talk with a brief overview of where you are going, a roadmap. In other words, tell them what you are about to tell them.
2. Next comes the body of the talk where your tell them what you have to say.
3. Finally, briefly summarize the main points you want the audience to leave you with. That is, tell them what you told them.

If this sounds redundant, it is supposed to. Remember, your audience is not taking notes and cannot remember all the details like you can, so providing frequent reminders is a useful way to keep them on track with you.

This first set of rules gives you a strategy for preparing the presentation, now we need some tactics. The second set of rules provide a more specific procedure to follow to fill in the details.

Rule set #2 (Tactics)

1. Begin with the end of your talk. What do you want to say, what is the point? For example, if you are launching rocks from your catapult to smash down the castle walls, your presentation to the commanding officer should probably end with a clear statement of how fast you are making holes in the walls, the location of these holes and how big they are. This would be the point of your presentation. This is what the presentation is all about. Once you have identified this idea, concept, piece of data, or graph, you are well on your way. Identify this first since it is the most important part of the talk.
2. Now, jump to the beginning of the talk. You now know where you want to go, but where do you start? You want to start at a place where you audience can understand what you have to say. As the field catapult commander, you wouldn't begin by explaining the new assembly-line technique you use for getting really big rocks to your catapult until you first explain where you have to go to get the rocks. You must first decide what you audience already knows about the subject at hand. Here, this is easy. The rest of the class probably knows about what you knew when you started the lab project. Starting here will insure that everybody understands what you are talking about. And this is the point, right?
3. Now that the beginning and end are specified, the middle is easy. Make a list of the ideas and equations you are assuming that your audience knows at the beginning and a list of things that they need to understand by the end of your presentation. The main body of your talk will fill the gap. Everything on the end-of-talk list that is not on the beginning-of-talk list must be explained in a way that assumes only things on the beginning-of-talk list. Once you've done this, your presentation is prepared.

 

The actual presentation

Once you have everything figured out, you are ready to assemble the presentation. The primary tool a scientist uses to give a presentation is the slide. Since we remember little of what we hear and only half of what we see, slides provide a way to show your audience what you are doing and improve the transfer of information tremendously.

There are three slides that are required: A title slide to tell the audience who you are and what you are going to talk about, a slide that shows the main graph, diagram, calculation, or data summary from your experiment, and a summary/conclusion slide that tells the audience what you want them to know (the point of the talk). Other slides will probably be needed to explain these but are not nearly as important as these three.

Once you have these three made, fill in the missing pieces as described in our tactical rule set (set #2). Think of the slides as paragraphs in a paper: every time you change main topics, change slides. This should occur no more frequently that about once a minute or minute and a half. Thus, for a 10 minute presentation, you should have no more than 7-10 slides. It takes about a minute to say anything useful and coherent on any topic so this is a rule of thumb rooted in the way we normally talk to each other. One/minute is an upper limit, fewer is better.

 

Making readable slides

Don't just make slides of your written report and expect to do well. For starters, the text is just too small to be read from the back of the room. Also, people naturally try to read what ever you put in front of them. If you put up a page full of text, they will begin by trying to read it all and not listen to you. Once they realize that they cannot see what you've put up, they loose interest quickly and tune you out.

The rule of thumb for preparing slides is that the text should be printed large enough for you to easily read at arm's length. This corresponds to at least 20 point type, preferably larger. If you can do that, then when it is projected, people at the back of the room can read what is written. Of course, neatness counts. This, of course, limits the amount of information you can put on one slide. This is good. You only need enough information to fill one or two minutes of discussion. Since you should never put up information on a slide that you don't explain, a minute's worth of talking doesn't need much material anyway, so this really isn't a serious limit.

Slides are really there to help you as much the audience. They provide a kind of public outline for what you are saying to keep you and the audience on track. By putting this outline on the slide, you don't have your face buried in a sheet of paper with your outline on it. You can point to the items on your slide as you explain them to the class. This makes for a much less boring presentation (think about boring lectures you've sat through).

On the slides, bulleted lists are good. The idea is to have the slide tell the audience the key points of what you are telling them is, not the other way around. Don't just stand and read the slide. It should summarize what you say, you shouldn't summarize what it says.

When you put a slide up that shows a graph, explain it to the audience. Explain the labels and units on the axes. Tell them the origin of the numbers you have plotted. Tell them what the slope or y-intercept (as appropriate) mean. Guide them through the plot so when you finish they know what you know about the figure. If you just put a slide with a graph of your data and say "Here are the results of our experiment" and then just stand there, at least two bad things will happen: 1) you will move on to the next slide too quickly and no one will have to understand what you've shown them and 2) you haven't told anyone what to look for in the graph. Remember, not everyone in the room knows the experiment as well as you do and nobody knows your data at all.

 

Answering questions

At the end of your presentation, you will be asked questions. Contrary to popular opinion, this is a good thing. This means that people paid attention to you and understood at least a portion of what you had to say. Don't be shy about wading right in to the questions. In this class, if you don't know the answer, chances are that others in the class don't either. The TA is there to help sort out the answer, even if the TA asked the question. Naturally, the better prepared you are, the easier this part of the presentation will be.

 

Remember: you are now the class expert on the lab project you just did.