Visual aids are an important factor in a successful
engineering or science presentation, and as a speaker, you should give careful consideration to your approach to
visual aids. Unfortunately, many presenters rely on the default settings provided by PowerPoint to
create slides for their presentations. Typically, this approach results in tiresome slides heavy with bulleted text
and perhaps an occasional image.
As a presenter, you should consider if this traditional slide
design is in fact the best method for communicating scientific information. What research exists that supports the
effectiveness of much bulleted text and the occasional image for the communication of scientific information? Since
slides are omnipresent in technical presentations, this question deserves some consideration.
Here, we strongly advocate for the use of the Assertion-Evidence slide design as a more effective alternative to the traditional bulleted
text approach.Research has shown that the Assertion-Evidence slide design is more understandable,
memorable, and persuasive than the traditional design in presenting scientific information. The
Assertion-Evidence slide design is characterized by a concise, complete sentence headline (no longer than 2
lines) that states the main assertion of the slide (i.e. what you want the audience to know as a result of the
slide) and the body of the slide consists of visual evidence for that assertion (charts, graphs, images,
You are strongly encouraged to research and learn more about
the Assertion-Evidence design. More details are not discussed here because all facets of this design are covered in
excellent depth on a partner website “Rethinking the Design of Presentations Slides” (first Google listing for the search term
Even if you are skeptical, challenge yourself to learn about
and utilize this design for your next presentation. We believe that you will find that your talk is more focused
and that great potential exists for your audience to gain more understanding about your subject matter.
Note that it will likely take you longer to create slides when
using this design. An inherent benefit of the headline assertion on each slide is that it forces the presenter to
articulate the purpose of the slide and to consider how that slide fits into the overall argument—this can take
some time. However, this is time well spent as it typically results in a more focused presentation.
So, how should you get started? It is
critical that you begin with the template (a .ppt file) that is provided on the website “Rethinking the Design of Presentation Slides.” This file can be found on the left side
of the page under "Assertion-Evidence Templates." This will help you to overcome the weak defaults of
PowerPoint. Additionally, here is a summary of the recommendations for style, typography, and layout of
Assertion-Evidence presentation slides.
Guidelines for Assertion-Evidence Slides [Alley, 2003]
1. Begin each
body slide with a sentence-assertion headline that is left justified and no more than two lines
the assertion headline with visual evidence: photographs, drawings, graphs, or words and equations arranged
1. Use a bold
sans serif typeface such as Arialor Calibri
2. Use 28
point type for the headline, 18–24 point type for the body text, and reference listings in 14 points
setting text in all capital letters, in italics, or in underline
blocks of text, including headlines, to one or two lines
2. Keep lists
to two, three, or four items
generous with white space, especially between text blocks and graphic elements within the slide
Examples of Assertion-Evidence Slides
Alley, Michael (2003).
The Craft of Scientific Presentations. New York: Springer, p.
Miller, Genevieve (2008).
Presentation given in CAS 100A for Engineers. Penn State.
It is our goal that you will choose to
adopt the Assertion-Evidence slide design as a successful strategy to make your technical presentations immediately
Tips for Using
Now let’s discuss a few tips for the use of slides in your presentations:
1.Overcome PowerPoint's weak
defaults.Begin designing your slides with the
template provided by the website “Re-thinking the Design of Presentation Slides”. The template can be
found on the left side of the page. Don’t underestimate the importance of this template in trying to overcome the
weak defaults of PowerPoint.
2.How many slides?Many presenters want to know
how many slides they should have. You should aim to have no more than one slide for every 1-2 minutes
of presentation time (20 minute talk, approx. 10 slides recommended). If your number of slides exceeds this, you
risk not providing your audience with enough time to absorb the information from your slides.
3.Discuss your slides.It is important that you
directly discuss and incorporate your slides into you talk. Don’t assume that your audience will just
figure it out for themselves. Many presenters will click through slides without directly mentioning and discussing
their content. You are essentially the tour guide about your topic during the presentation—the slides are an
important stop on that tour!
4.Practice with the
equipment. Make sure you know how your slide advancer works. It is distracting to the
audience if you are fumbling with the equipment and it will only serve to make you more nervous. Just arriving a
bit early to the room that you are presenting in and familiarizing yourself with the environment and equipment can
eliminate many of these issues.
5.Practice with your
slides. It is damaging to your credibility as a presenter if you are clicking back and forth
“searching” for the slide that you want to discuss. You should know precisely where and when each slide is coming
in the presentation. A good tip is to put a Post-It note on your computer that lists the numbers of your important
slides. This way, if you do need to jump to a slide, you can just type that number into your computer, hit “Enter,”
and the screen will jump right to that slide. This is much more professional that clicking back through 12 slides
during a Q & A session because an audience member had a question about a slide that appeared early in the
environment. Be sure to take control of the
lighting so that your slides can be seen to their best advantage. Many times the lights on top of the
screen are left on and the resulting glare makes slides look washed out and difficult to see.
7.Use the laser pointer
sparingly. If you have shaky hands, the laser pointer only serves as beacon emphasizing your
nerves to the audience. If precision of location is important, It might be more effective to use your slide
software (animate a circle or arrow) to emphasize the area that you want to highlight for your audience. An
old-fashioned pointing stick can be effective also.
8.Slides aren't always
neccessary.Perhaps the most important thing to know
when using slides in a presentation is when to turn them off. There is no rule that says that it is a
good idea to be show slides during the entire talk. Slides are not always the best medium for your information and
you should get into the habit of asking yourself, “Is a slide necessary?”. For example, if you are discussing a
personal experience or observation, that information might be more effectively communicated without a slide.
Additionally, your slides should not be visible unless they are relevant to what you are currently discussing in
your talk. When you finish with the point discussed in a slide, choose to blank the screen so that the audience
focuses entirely on you. Blanking the screen can be one of your most powerful tools because it refocuses the
attention of the audience onto you.
9.Slides aren’t the only option for
visual aids. Don’t be afraid to think outside the box and consider other types of visual aids
such as demonstrations and videos. We can see great examples of how these are used effectively with our model
presenters. Scott Fishbone uses a flashlight demonstration to great advantage when highlighting the differences
between xenon and halogen lighting. David Gallo uses video footage to provide a definite “wow” factor to his
presentation. Would his use of visual aids have been nearly as effective if he would have chosen to show still
images of the sea creatures? Definitely not. Of course, it is essential that you practice and prepare to smoothly
incorporate alternative visual aids into your presentation.
This presentation has many strengths (such as structure),
but here we will focus on this presenter’s excellent use of visual aids. It is clear that this
presenter has thought critically about how to best communicate her technical information visually to the
audience. She has very carefully crafted headlines on each slide that communicate the key
information to her audience, and the body of the slides contains excellent images that illustrate the information
from the headline visually. As you review each slide, notice the strong relationship
between the headline and the corresponding visual evidence. Had this presenter employed the
traditional bulleted list design of slides, the audience would have not gained nearly as much understanding of this
Slides 1 and 2 (1:30)
These slides clearly introduce the audience to the key terms
and conditions that they must know in order to understand the function and limitations of the typical culture
system. The illustration of the macromolecules and waste products gives us a concrete representation
of the dramatic shift that occurs in the environment when the medium is changed. Notice how
the headlines of each slide provide a clear focus for what the listener is to obtain from the slide.
The placement of this slide in the presentation is
critical. It is natural that the audience would want to see a picture of what an actual bioreactor
looks like, but it is important that the speaker provides this information at the right
time. Had she showed this slide in the introduction when she first mentions the bioreactor,
the audience would not have had an appreciation for what goes in inside a cell culture system, so they would not
have gotten as much out of her explanation of the different compartments in the
bioreactor. Now that we have already seen the illustration from Slides 1 & 2, we
understand the functions of those compartments. Moreover, we are now ready to move on and
understand the unique properties of the bioreactor. Had she showed this slide after she
discusses the unique properties of the bioreactor, it would not have had as much impact because it would be coming
too late. Finally, notice her use of the red circles to highlight the compartments as she
is discussing them. This is an effective method of indicating important areas on an image
rather than using a laser pointer. A laser pointer would have been much more distracting in
Slides 4 and
These are perhaps the most memorable slides of the
presentation—these are ones that the audience is likely to talk about even after they have left the
presentation. This simple, yet powerful animation allows the audience to see the unique function of
the bioreactor, and the speaker is able to highlight a key part of the research which is how the stability of the
cell environment is achieved. Because of how memorable these images are and how clearly
they communicate the relevant information, it is likely that an audience who did not know much about the topic
would be able to explain the basic qualities of the bioreactor weeks after seeing this
talk. You will want to consider in your own presentations what type of images you might be
able to provide that will “stick” with the audience.
Slides 6 and 7
These slides begin the part of the talk where the presenter
is discussing the results and application of the work with the bioreactor. Again, because this
information is represented visually, rather than through text and bulleted lists, it is much more likely to be
remembered by the audience. Also, the speaker does an excellent job of walking the audience
through the images and pointing out the specific parts that they should notice. The images
on Slide 7 are very compelling, and the labels that are applied below each one are helpful in distinguishing what
is being seen. This is an example of the appropriate use of text in the body of the
This presenter’s topic
lends itself to highly visual evidence since it deals with light, and this presenter recognizes and seizes the
opportunity. As a result, the visual aids are a crucial element in
the success of this presentation. This talk is significantly more
engaging because of the use of visual aids. The key argument that
this speaker is trying to make with his presentation is that xenon headlights are superior to halogen
headlights. The proof of this assertion lies in a comparison of
performance between the two technologies, and this is the strategy that the speaker utilizes when designing his
Slide 1 (1:00)
This speaker begins his
presentation by establishing the importance of proper headline function by discussing the problems that occur in
part because of poorly performing headlights. The headline of this
slide summarizes the key problems and the picture is one that could stir emotion and raise concern within the
audience. Perhaps some audience members have had an experience very
similar to the one represented in the picture or even just visualizing something similar happening to them
personally is certainly enough to raise concern. This is effective
because it invests the audience in the importance of improving these problems.
Slide 2 (1:42)
This slide serves the
purpose of emphasizing the main assertion of the talk. This is
accompanied by an image that provides a visual anchor for the assertion.
Slides 3, 4, 5, and 6 (2:06)
This series of slides uses
images of comparison very powerfully. Each slide focuses on a
direct comparison of various characteristics between halogen and xenon headlights. The main assertion of the talk is to prove the superiority of xenon
headlights. The speaker provides much evidence for this assertion
by showing the major difference. There is truth to the saying,
“Seeing is believing.” By showing the image comparisons as he
analyzes each performance characteristic of the lights, the audience is able to make the judgment for themselves
after analyzing the visual evidence. Another presenter might
have just chosen to present the comparison with a table of data (e.g. amount of lumens, percent of peripheral area that receives light,
etc.). Imagine how different this presentation would have been if
that approach had been taken! Fortunately, this presenter uses his
slides to his maximum advantage, and as a result, his presentation makes a compelling argument for the
advantages of xenon headlights.
perhaps one of the most compelling parts of this presentation because the audience is able to see firsthand the
difference between the two technologies, and the reason that it succeeds is because the comparison is so
striking. This speaker stepped “outside of the box” in terms of using a visual that was not a slide, and it was
a great success. We are so conditioned to use slides as our only visual medium, so we can forget that there are
often much better ways to visually represent information and ideas. Demonstrations can be incredibly effective
because they get the audience involved and make them feel a part of the action because they are witnessing
something firsthand, instead of seeing it on a slide after it has occurred.
This presenter’s visual aids are a
strength of this presentation. There are two elements that
stand out about this presenter’s use of visuals. First, this
presenter uses a variety of different types of visual evidence, which makes the visuals dynamic and will appeal
to a variety of audiences. Secondly, this presenter
incorporates his visuals very well. He discusses them
specifically and indicates to the audience the key areas that they should notice in each image. Let’s look at each slide individually and discuss its function in the
Slide 1 (2:04)
first visual is used to support the speaker’s assertion that solar energy’s abundance makes it the best
candidate for our energy needs. The image chosen by this
speaker is highly effective because it is so striking. The
audience is able to see very clearly the different colors that delineate the different regions of exposure to
solar energy, and the speaker incorporates this visual well by pointing out the key colors of orange, yellow,
and green. Furthermore, he emphasizes that most of the highest
populations are contained within the high energy region which supports the argument that he is making and the
listener is able to verify this through this visual image.
Slide 2 (4:55)
was a well-chosen visual because the chart clearly shows an upward trend, which is important to the argument
that the speaker is making. Additionally, this chart provides
a point comparison between the original technology of crystalline silicon and the new technology of thin
film. This is a key piece of evidence as the speaker argues
that the coming technologies are becoming more and more viable and efficient.
Slide 3 (5:41)
this stage in the presentation, the speaker is explaining the new technology developments. This slide serves to engage the interest of the audience because they can
see how these technologies would actually look and function on a home. Note the use of the animation “appear” for the second
image. This is a good choice because the speaker didn’t
want to focus on that image right away, so it made sense to bring it in when he got to that point in the
talk. There are very few scenarios in technical
presentations when it is wise to use an animation type other than “appear”. Typically, the use of other types of animation only serves to distract
from the content of the presentation and should be avoided.
Slide 4 (7:20)
headline of this slide is particularly strong because it focuses the audience directly on the key assertion of
this slide—that the new technologies are using less material while being more efficient. The graph provides evidence for this assertion, and the speaker points
out that amorphous silicon (a-Si) performs markedly well in this area.