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Unformatted text preview: Rethinking the Design of Presentation Slides: the Assertion-Evidence Design 11/8/08 5:33 PM Rethinking the Design of Presentation Slides: The Assertion-Evidence Structure Assertion- Evidence Models
Center for Disease Control
Penn State (1)
Penn State (2)
Simula Research Lab
Assertion- Evidence Templates
Teaching Slides (2003)
Criticism of Traditional Design
Gomes, Wall Street Journal
Parker, New Yorker
Schwartz, New York Times Recently, much criticism has arisen about the design of slides created
with Microsoft PowerPoint. This web page challenges PowerPoint's
default design of a single word or short phrase headline supported by
a bullet list. Rather than subscribing to Microsoft's topic- subtopic
design for slides, this web page advocates an assertion- evidence
structure, which is shown in Figure 1 and which serves presentations
that have the purpose of informing and persuading audiences about
technical content. This structure, which features a sentence - assertion
headline supported by visual evidence, is documented in Chapter 4 of
The Craft of Scientific Presentations, a November 2005 article in
Technical Communication, and the presentation "Rethinking the
Design of Presentation Slides." Assertion- Evidence Design: Talks
Doumont, IEEE - PCS Talk, 2007 (audio)
Alley, USGS Talk, 2005 (video)
Alley, SPIE Webinar, 2007 (pdf)
Assertion- Evidence Design: Research
Geoscience Education (January 2007)
Tech Comm (May 2006)
Tech Comm (November 2005)
FIE (October 2005)
More Assertion- Evidence Models
Norwegian Inst. Air Research
Penn State (3)
University of Illinois
US Geological Survey http://writing.engr.psu.edu/slides.html Figure 1. Example of a well designed slide [Zess and Thole, 2001]. Three key assumptions exist for using the assertion- evidence
structure. The first is that slides are an appropriate visual aid for
the presentation. Too often, slides are projected when no visual
aid would better serve the presentation. Second, the success of
the presentation hangs on the audience understanding the
content. Finally, the primary purpose of the slides is to help the
audience understand the content, rather than to provide talking
points for the speaker.
For a number of years, others have advocated an assertionevidence structure for slides in engineering and scientific
presentations. These advocates include Larry Gottlieb
Page 1 of 9 Rethinking the Design of Presentation Slides: the Assertion-Evidence Design 11/8/08 5:33 PM (Lawrence Livermore National Lab), Hugh Keedy (Vanderbilt),
Bob Leedom (Northrop Grumman), Jean - luc Doumont
( Principiæ ), and Cliff Atkinson ( Sociable Media). In addition,
instructors such as Rick Gilbert and his team of trainers at
PowerSpeaking, Inc., have recently started teaching this slide
structure. To make it easier for you to adopt this structure, this
web page provides a special PowerPoint template that you can
download to your computer and modify to communicate your
content to your audience. Also, to provide you with models, this
web- page presents several student and professional examples
that follow this structure. Each year, more than 250 million copies of Microsoft
PowerPoint produce trillions of presentation slides
worldwide [Doumont, 2005]. Many of these presentation
slides, which can be overhead transparencies or computer
projections, are created by presenters in science and
engineering. Because presentation slides reduce the personal
connections between the presenter and audience, presenters
have to be critical thinkers about when this medium is
appropriate and when it is not [Alley, 2003]. Despite this
decrease in personal connection, slides are still valuable in
scientific and technical presentations, especially when the
audience needs to see images or visual relationships to
understand the content.
Because of its dominant 95 percent of market share
[Parker, 2001], Microsoft PowerPoint and its defaults
have greatly affected the design of these presentation
slides. For that reason, most slides that are shown in
science and engineering presentations have short
phrase headlines supported either by bullet lists or by
bullet lists and images [Gaudelli et al., 2008]. In
essence, this design calls for a topic- subtopic view of
the content. Recently, harsh criticism of this design of
presentation slides has surfaced in several popular
publications: Schwartz, "The Level of Discourse
Continues to Slide," New York Times ; Parker,
"Absolute PowerPoint," New Yorker; Tufte,
"PowerPoint Is Evil," Wired ; and Keller, "Is
PowerPoint the Devil? " Chicago Tribune. A common
theme in these articles is that the presentation slides
that follow Microsoft PowerPoint's defaults
oversimplify the subject matter, sometimes with
http://writing.engr.psu.edu/slides.html Figure 2. Example of a well designed slide [Bruaset, 2007]. Figure 3. Example of a well designed slide [Marthinsen et al., 2004]. Page 2 of 9 Rethinking the Design of Presentation Slides: the Assertion-Evidence Design 11/8/08 5:33 PM Figure 3. Example of a well designed slide [Marthinsen et al., 2004]. serious consequences. For instance, in the official
investigative report about the Space Shuttle Columbia
disaster, Yale professor Edward Tufte argues that
traditional slides failed to characterize the risk that the
ill - fated Columbia faced from its collision with debris
at lift- off [Tufte, 2003b]. Another common theme of
these articles is that the design quickly becomes
monotonous for audiences, thus making it difficult to
According to Larry Gottlieb, a presentation instructor
at Lawrence Livermore National Laboratory, one
failing of traditional slides lies in the use of the phrase
headlines that leaves unclear the purpose of the slide
[Gottlieb, 2002]. Since the 1980s, Gottlieb  and
others [Keedy, 1982; Alley, 2003; Doumont, 2005;
Atkinson, 2005; Leedom, 2005] have rejected phrase
headlines and, instead, have advocated a short
sentence headline that states the main assertion of the
slide. Note that just having a headline in the form of a
sentence is not enough. As Bob Leedom  states,
that sentence has to state the main message of the
slide. In fact, one of the Space Shuttle Columbia
slides that Tufte critiqued [2003b] had a sentence
headline; the problem was that sentence did not at all
capture the main assertion of the slide.
Another failing of the traditional design of slides,
according to Edward Tufte, is the reliance on bullet
lists to provide cogent evidence for assertions [Tufte,
2003a]. As Shaw, Brown, and Bromiley  point
out in a Harvard Business Review article, bullets are
"too generic," they "leave critical assumptions
unstated," and they "leave critical relationships
unspecified." Figure 4. Transformation of a teaching slide from the traditional
design to the assertion - evidence design [Robertshaw, 2004]. Assertion-Evidence Slide Design: A
As mentioned, over the past two decades, several
people have advocated a slide design that is distinctly
different from what Microsoft PowerPoint promotes
with its defaults. This alternative slide design features
a succinct sentence headline that states the main
assertion of the slide. That assertion is then supported
by evidence presented in a visual manner. Presented in
Figure 2 and Figure 3 are excellent examples of this
design. Each headline states the principal assertion of
http://writing.engr.psu.edu/slides.html Page 3 of 9 Rethinking the Design of Presentation Slides: the Assertion-Evidence Design the slide, and each slide body supports that assertion
in a visual manner. In each slide body, words are
incorporated, but only as needed. Bullet lists are not
This assertion- evidence design, which was presented
in a November 2005 article in Technical
Communication [Alley and Neeley, 2005], addresses
the two mentioned weaknesses of the traditional
design: unclear main assertion and lack of connections
in the evidence. In addition, this assertion- evidence
design addresses many of the weak typography and
layout defaults of Microsoft PowerPoint. For instance,
the new design calls for specific stylistic, typographic,
layout, and animation guidelines that have arisen from
more than 150 critique sessions, run by Alley, of
engineering and scientific presentations at universities,
in industry, and at national laboratories. Given in
Figure 3 is a contrast of a teaching slide that uses the
traditional topic- subtopic design and this new
assertion- evidence design.
Several advantages exist to using this assertionevidence design [Alley and Neeley, 2005]. First, the
assertion headline more readily orients the audience
during the presentation to the purpose of each slide.
Second, having a sentence headline allows the
presenter to clearly emphasize the most important
assertion of the slide by giving that assertion more
typographical emphasis than it would receive in a
bullet list within the body of a traditional slide. Third,
according to Professor Stacy Gleixner  who
heads the NSF PRiME project for teaching materials
science and who has converted the slides in that
project to this design, "Following the design would
improve my lectures even if the old slides were
projected, because when I create a sentence headline,
I think about what main assertion I want the students
to remember from that slide. Just that act makes my
lectures more focused."
Visual evidence in the body of the slide also has major
advantages over the traditional bullet list. According
to Professor Richard Mayer's principles  for
multimedia design, audiences learn better from
relevant images coupled with words than from words
alone. Mayer, a well regarded cognitive researcher
from the University of California at Santa Barbara,
also asserts that multimedia is more effective when
images are placed close to and presented
http://writing.engr.psu.edu/slides.html 11/8/08 5:33 PM Figure 5. Comparison of test score of 71% for a slide with a
traditional design, shown left, with a test score of 82% correct for the
new assertion - evidence design on the right: statistical level of
significance < 0.05. The test question, which was at the knowledge
level of Bloom's taxonomy, asked the 200 students in each section to
state how much of the world's resources the United States uses. Figure 6. Ratio of the test scores for the group that was taught from
the assertion - evidence slides to the test scores of a similar- sized group
that was taught with traditional slides [Alley et al., 2005]. Bars 1- 8
(light blue) represent significant increases, while bars 9- 19 (black)
represent differences that were not significant. For these two 200student sections, the test scores on these identical questions increased
from 71% to 80% (p < 0.001). These questions tested students at the
knowledge and comprehension levels of Bloom's taxonomy. Page 4 of 9 Rethinking the Design of Presentation Slides: the Assertion-Evidence Design 11/8/08 5:33 PM simultaneously with corresponding text. The assertionevidence design that is advocated by this web page
follows these two principles. Moreover, the
requirement of a visual representation in the teaching
slide design of this study addresses the major
weakness of relying on bullet lists: not making clear
the connections between details [Shaw et al., 1998].
As was shown in the transformed slide of Figure 5, the
unclear relationships among the elements of the topicsubtopic slide (left) are clarified in the assertionevidence slide (right).
Recent experimental tests have shown that the
assertion- evidence slide design is superior to the
traditional design at communicating technical
information to an audience. Studies have shown that
using the assertion- evidence design in the teaching
slides of a large geoscience course led to statistically
significant increases (p < 0.001) in the knowledge and
comprehension levels of students of course material
[Alley et al., 2005]. Those increases are especially
evident when the information to be understood and
retained lies in the sentence headline [Alley, et al.
2006]. Figure 6 shows an example of a transformation
in a teaching slide that led to a statistically significant
increase in test scores for a large introductory course
in geoscience, and Figure 5 shows a comparison of
the test scores from one intervention [Alley et al.,
2005]. The testing occurred between historical
sections having the same instructor, room, semester
time slot, class size (200 students), and number of
projected teaching slides.
Several underlying assumptions exist for when the
assertion- evidence design should be used. The first
assumption is that slides are, in fact, the appropriate
visual aid for the presentation. A common criticism of
presentation slides is that the medium is used for
presentations in which a different visual aid or, more
commonly, no visual aid would be appropriate. A
second underlying assumption is that the success of
the presentation depends on the audience
understanding the content. Generally, when engineers
and scientists use this design, they receive more
questions than if they had used the traditional topicsubtopic design. The reason is that the audience better
understands the content. Yet a third underlying
assumption for using the assertion- evidence design is
that the slides are a visual aid for the audience rather
http://writing.engr.psu.edu/slides.html Page 5 of 9 Rethinking the Design of Presentation Slides: the Assertion-Evidence Design 11/8/08 5:33 PM than a visual aid for the speaker. One allure of
PowerPoint that critics cite is that it allows presenters
to project their "talking points." The assertionevidence design, on the other hand, presents only the
key assertions of the talk, forcing the speaker to know
the content well enough that he or she can speak from
the assertions and the supporting visual evidence.
A key disadvantage to using this design is that the
design requires more time on the part of the presenter
than the traditional topic- subtopic design. Not only is
more time required to create visual evidence, but more
time is needed to craft a succinct sentence headline
that states the main assertion of the slide. A second
disadvantage is that the design is more challenging
than the traditional topic- subtopic design. To create
those sentence - assertion headlines, the presenter has
to understand purpose and relative importance of
details. Yet a third disadvantage is that because this
design is so different from what commonly is
projected in meeting rooms, classrooms, and
professional conferences, a resistance sometimes
arises from co - presenters and supervisors to try a
different approach. Conclusion: Effects of Adoption of
Alternative Slide Design
Preliminary research suggests that if engineers,
scientists, and technical professionals would adopt this
assertion- evidence design for those presentations in
which slides are the appropriate medium, the
effectiveness of those presentations would increase
significantly. Likewise, if educators of engineering
and science would adopt this slide design for teaching
situations in which presentation slides are an
appropriate teaching tool, the comprehension and
retention by students in those engineering and science
courses would increase significantly, especially if this
slide design is used with active learning measures
[Alley et al., 2007]. What is needed are more such
tests in different disciplines of science and
engineering. Also needed are more tests at different
levels of Bloom's taxonomy of learning.
This assertion- evidence design demands much more
from the presenter than simply following the defaults
of PowerPoint. For one thing, identifying the main
http://writing.engr.psu.edu/slides.html Page 6 of 9 Rethinking the Design of Presentation Slides: the Assertion-Evidence Design 11/8/08 5:33 PM sentence assertion of each slide requires more thinking
than simply identifying the slide's topic word or
phrase. In addition, coming up with cogent visual
evidence to support each assertion is more demanding
than coming up with a bullet list of subtopics for each
slide topic. Another hurdle to adopting the design
arises from overcoming the weak defaults of
PowerPoint for type size, type placement, text anchors,
bulleted text, and distracting backgrounds. To help
presenters overcome these weak defaults, this web site
this web page provides a PowerPoint template that
presenters can download and modify. References
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Last updated 08/2008
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