Courant Institute New York University FAS CAS GSAS

On teaching with slides

Wednesday, January 19, 2011 - 1:53pm

Interesting editorial by Danielle Fleischman of the Indiana Daily Student about "The Power of PowerPoint"

When it comes to learning in the 21st century, the use of computer-generated slides is a no-brainer. Students prefer to have the visual aide during lectures, claiming that it helps them to maintain interest and retain material.

Unfortunately, the quality of PowerPoint presentations varies from professor to professor.

She gives suggestions for best practices when using slides in lectures. I started to leave a long-winded comment but then thought it would make a better blog post.

Before I go further, let me lament that "PowerPoint" has become a genericized trademark: a brand name like "Kleenex" taking the place of a noun like "facial tissue". My lecture slides are not done in PowerPoint, they are done in LaTeX with the beamer package. This is a must for slideshows containing a lot of math. For first-day-of-class and contributed talks I often use Keynote.

Also, the feedback I get on the use (not the quality) of slideshows for math courses is decidedly mixed. After midterm evaluations, I usually prepare a slide about slides to show students their own division of opinion on the subject, and my reasons for using slides. Students who struggle with the mechanics of solving equations can be overwhelmed with having large amounts of math just whiz by on the slides. And in general it's probably impossible to write down what's on the slides at the same speed it appears on the screen. It helps to step out long derivations and solutions piece-by-piece to narrow focus, and providing the slides to the students for notetaking helps.

Now to some of Ms. Fleischman's suggestions:

All too often, instructors get carried away with their PowerPoints and upon presentation, it seems more like an art project then a learning tool. Research has proven that simple slides without fancy transitions and complicated backgrounds provide the best learning tools for students. What’s more, any irrelevant pictures, sounds or graphics have been found to be detrimental to the learning process.

There are a lot of studies mentioned in the editorial that aren't cited, but even as opinions they're worth paying attention to. I'd have to agree that transitions, sounds, and graphics for their own sake can be distracting. I wouldn't totally eliminate them but they should be used with care. For instance, in my recent talk on Mashups for course websites with Yahoo! Pipes, I used the Magic Motion transition to take a screenshot and zoom in on a portion of that screenshot I wanted to talk about. I used wipes when switching from screenshots from one website to those from another. The dissolve transition is a nice one to use if you simply must have one, but many times you can avoid it.

(Why are all these fancy build-ins and transitions in the software if you shouldn't use them? I think that they work well for presentations which are not for lectures, but for kiosk displays. You can draw attention to the text and graphics when there's no human there to narrate.)

When it comes to PowerPoint, brevity is often the name of the game. However, one study indicates that full-sentence headlines written as an assertion are more effective than a single word or phrase at the top of the page.

You have to strike a balance between the in-class audience and the asynchronous audience using the slides to study. I opt for brevity when giving talks because I don't want my slides to overshadow me (If everything's on the slide, what value do I add standing in front of it?) But in my recent pass through Calculus I I made an effort to make sure every slide had a title that was descriptive of what was going on on that slide. Textbooks use callouts and colored items to guide the reader into the framework of the material, and slides should do the same.

Another piece of research suggests that the fonts Gill Sans and Souvenir Lt are the easiest to read on a PowerPoint and in fact help with material retention.

Gill Sans is the default Keynote font and is definitely pretty. On the other hand, you run the risk of overusing it and having people think you don't know enough about slides to choose your own font. I don't have an opinion on Souvenir Lt. But in general I would agree that sans-serif fonts are best for screen displays.

This term I'll be participating in the NYU's Open Education program, and they've asked me to use their branding, which is Gotham, Calibri, and Cambria Math. Those are all good for slides.

And while there is no research available to back up this claim, I can write from my own experience that performance in a class is enhanced when professors upload their PowerPoint slides before the day’s lesson. This provides students with an outline of the lecture and allows for easier note-taking.

However, it is too often that an instructor claims that they cannot provide the PowerPoint before class. Well, as a student, I am expected to have my work done before class starts. Can the same not be asked of our professors?

Guilty, sometimes. I can see the merit in the students' request. For several reasons I can't always do it.

Slides may not actually be ready until the beginning of class. The student is correct that she's expected to have her work done before class starts, and I comply with the same expectation. Does she have her work done the day before class? To me, there's nothing like the fierce urgency of now to stimulate good lesson planning. Which might be another way of saying I'm a procrastinator, which makes it a good thing that I can improve existing slides from year to year of a course.

Also, while I want to help students with retaining the course material, I'm not willing to enable students who want to substitute flipping through the slides for actually participating in class. And I don't want to reinforce the opinion that all I do in class is read through recycled slides.

Finally, I have jokes on my slides and I don't want to give them away before class!

But now that I have a good base of Calculus I material to build slides on, I've been able to work this way: Before class I prepare a handout version of the slides that's on letter size paper, three slides to a page, with note lines on the side. For instance, this recent slideshow on integration by substitution:

On the handout I blank out material that I don't want to give out until class. For instance, if I'm teaching a new concept and giving examples, the first example will have its solution on the handout, but the next ones will not. Before class students can try those examples, and during class they can fill in the correct answers. Having it formatted for paper encourages students to print it out and writing on it rather than flip through it on their laptops (and all the distractions they invite) during class.

To my advantage, if I don't have the solution typed up yet, I can put it off finishing that part until the day of class. So the handout is a framework for class but not the entire class. I can also eliminate my jokes from the handout version.

(This is another advantage of beamer over PowerPoint/Keynote: I can do this kind of thing programmatically. I have one master file which produces the handout version and the in-class version, and which allows me to mark stuff that goes in one but not the other).

After class I take the in-class version of the slides, and based on questions, decide if there's material I want to add. Then I upload the in-class version.

This workflow allows students who want to bring a version of the slides to class to aid their notetaking without eliminating the role of the lecturer in presenting the material. Students who want to skip class can still download the slides after class, but the only way to prevent that would be to not upload anything, and that doesn't seem fair to those who want to use the slides wisely. And it does require a bit of forethought and programming. But I'm pretty happy with what it has evolved to.

Technology is dragging the institution of learning into the future whether it wants to go or not. So isn’t it about time [professors] treat PowerPoint as a tool instead of a toy? I certainly think so.