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AC 2009-1570: SKETCHING DURING MECHANICAL DESIGN: STUDYINGSKETCHING AT THE UNIVERSITY OF MARYLAND
Sophoria Westmoreland , University of MarylandSophoria Westmoreland is a Graduate Student at the University of Maryland in the Department ofMechanical Engineering. She completed her first bachelor's degree in General Engineering atClark Atlanta University and her second bachelor's degree in Mechanical Engineering at GeorgiaInstitute of Technology.
Ashley Grenier, University of MarylandAshley Grenier is an May 2008 Master's graduate from the University of Maryland in theDepartment of Mechanical Engineering.
Linda Schmidt, University of MarylandLinda C. Schmidt is an Associate Professor at the University of Maryland in the Department ofMechanical Engineering.
She completed her doctorate in Mechanical Engineering at Carnegie Mellon University anddeveloped a grammar-based, generate and optimize approach to mechanical design. Thedissertation title was "An Implementation Using Grammars of an Abstraction-Based Model ofMechanical Design for Design Optimization and Design Space Characterization." Her B.S. andM.S. degrees were granted by Iowa State University for work in Industrial Engineering with aspecialization in queuing theory, the theory of waiting in lines.
Her research interests include computational design, design optimization, and developing formalmethods for design. Her educational interests include the development of student project teamtraining materials to build more effective engineering student project teams.
Dr. Schmidt is the founder and director of the Designer Assistance Tool Laboratory (DATLab).She is a member of the American Society of Mechanical Engineers and the America Society ofEngineering Education.
© American Society for Engineering Education, 2009
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Sketching During Mechanical Design:
Studying Sketching at the University of Maryland
Abstract
The ability to create hand-drawn sketches is still a relevant skill for design engineering. [1]
The
idea that thoughts and cognitive processes can be captured by pencil and paper is the basic
essence of sketching. Engineers and architects alike have long been used sketching as a tool for
documenting mental processes, organizing ideas, creating plans, and presenting their ideas to
others via a comfortable medium. The authors present a sampling of literature to remind all that
sketching helps the designer work through his or her own cognitive processes in a self-
documenting fashion. This paper reports on the sketching habits of capstone design students at
The University of Maryland, College Park in the Department of Mechanical Engineering.
Student sketching skills were assessed using skill-based coding schemes and a content-based
coding scheme. A sketching importance lesson was given to students of one capstone design
course section and results in their sketching of project concepts were analyzed and compare to a
control group made up of another section. The sketching importance lesson focused on the value
of sketching for design not on how to sketch. A significant finding was that the sketching
importance lesson changed the type of sketches produced; the number of sketches produced by
the students (a reduction), and increased the number of details within sketches.
Key Words: sketching, cognition, engineering education, design documentation
1.0 Introduction
A survey of the panorama of mechanical engineering curricula reveals that the use of sketching
in the design process is vanishing. Students and instructors alike are drawn towards the latest
technological instruments for mechanical design. The enthusiastic adoption of CAD software in
engineering education left skills like pencil sketching, mechanical drawing and lettering back in
the last century. This is unfortunate because a preponderance of research literature on sketching
reports that the intentional use of sketching improves the mechanical engineering design
process.[2]
There is also a renewed appreciation of the link between sketching and creativity. This
is put succinctly by McCormick writing in the ASME monthly, Mechanical Engineering.
“Sketching is the tool for innovation, and is so vital to the engineering process that it should be
taught and used as an essential part of engineering education and professional practice”. [3]
The human mind is a complex system closed to typical forms of experimental observation of its
operations. Documenting and analyzing its internal workings during design may seem to be an
impossible task. However, researchers have found that sketches and design journals can provide
much insight into the student’s cognitive processes during design. [4-6]
Research methods are
required that can be applied to individual student design assignments to determine their level of
design process understanding.
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The authors developed a content-based sketching coding scheme to analyze the types of sketches
that students were using during mechanical design. The scheme was broadened to apply to visual
representations found in reports submitted for a capstone design course. The new coding scheme
was developed from previous research results in engineering design emphasizing team projects
and design cognition research. The content-based sketch coding scheme was first presented in a
2008 publication by Westmoreland et al.[7]
and is a tool to review type of visuals students use in
a variety of design scenarios. The ability of the coding scheme to differentiate visuals based on
details common to mechanical design issues (e.g., applied loads, motion indication arrows,
dimensions, and fits) is what distinguishes the coding scheme from others. This type of coding
scheme allows the user to perform quantitative analysis on sketches.
This paper presents the findings of three different studies (including a summary of the
Westmoreland 2008 work) [7]
on the use of sketching in the design process on graduating senior
students at the University of Maryland. The studies were conducted to answer the following
questions about sketching: What is the skill level of the students who are using sketching as a
tool for mechanical design? When are students using sketching in design documentation? What
will be the effect of a lesson on the importance of sketching on student sketching uses and skills
in a capstone design course? This paper describes each study and results pertinent to sketching
during design.
2.0 Literature Review
2.1 The importance of sketching
The act of sketching is a both physical and mental process. A popular description of sketching is
that a sketch is a designer’s ‘conversation with themselves’. Numerous studies have been
conducted on the cognitive processes that occur during sketching and some of those relevant
studies are discussed here. Tversky reinforces the importance of drawing as a design tool. One of
the products of drawing and sketching is the segmentation of concepts that are critical to thought
organization. [8]
Goel gives evidence in his work that a series of sketches often represent lateral
transformations in early design phases, such as changing the functional solution to a key system.
In contrast, as series of sketches during the final design phases (e.g. detail design) are often
vertical transformations or refinements of the same design. [9]
Combining engineering design and cognitive psychology views to analyze ideation effectiveness
through sketching, Shah et al. created an ideation measure for verbal descriptions o concepts.
The measures include on quantity, quality, novelty, and variety. A genealogical categorization
was created to better understand the different levels of sketch and differentiate physical
principles proposed in sketches generated for a design task. This was then used to create models
of ideation and sketching as well as in predicting performance in design projects. [10]
Designing a new product or structure comes with certain mental workloads relating to cognitive
activities. Externalizing some of these activities is assumed to relieve the load, as can be the case
in making a quick series of rough sketches to record a number of different concepts. Sketching
does not slow down this cognitive rate though. Bilda and Gero show that sketching promotes
cognitive activities and relieves working memory. [6]
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2.2 Skill-based coding scheme
Sketch coding schemes have been created to assess student sketching skill during the design
process. Two prominent sketch coding schemes include one by McGown[11]
and one by the team
of Yang and Cham[12].
McGown’s research produced a coding scheme to differentiate between
sketches done in the early stages of the design process. McGown’s research was conducted with
final year engineering students. A 5-level, sketch-coding scheme based upon displayed drawing
skills and complexity of sketches was created to better analyze and characterize sketches drawn
by students. (A description of the McGown sketch levels and examples of each can be found in
Table 1.) Yang and Cham’s scale was 5 levels assessing sketching skills based on criteria
including realism (proportion and accuracy), style, and detail. In their study of sketching skills of
student design teams, Yang and Cham only encountered sketches of levels 1, 2, and 3. The local
studies presented by the authors in this paper apply these skill-based coding schemes, also failing
to find any instances of sketches at the highest level of skill in the scheme. Details will be given
in the description of the studies in Section 3.
2.3 Link between sketching and thinking
A recent article in the Journal of Mechanical Design commented on the link between creativity
and sketching during the design process. Yang and Cham[12]
present results on correlating
sketching skills with design outcomes, concluding that student sketching skills vary and student
tendencies to sketch vary with skill levels and the perceived value of the sketching activity. This
fulfills the prediction of Ullman et al.[13]
reporting in 1990 that not all engineering students
sketch during design, even when they are taught to do so.
Robertson et al.[14]
studied the impact of CAD use on creativity as self-reported by 200
professionals and identified four relevant phenomena. The first is an increased ability to
communicate concepts and create shared visual understanding via the CAD model. The
remaining phenomena are less positive: circumscribed (or limited) thinking; premature solution
fixation, and bounded ideation. The Robertson work included a small focus group of recent
graduates leading them to reflect on CAD usage in education vs. in industry. Along with the
positive benefits of CAD skills (e.g. improved communication, ability to use current tools);
negative effects included an unrealistic belief in the accuracy of CAD models and the tendency
to equate CAD drawing with the act of design. A recent study at the University of Connecticut
compared student and instructor perceptions of creativity in the fields of engineering, science and
humanities. [15]
Engineering students were found to lack a creative work process.
Grenier and Schmidt analyzed student design journals sketches and notations of students at The
University of Maryland during a 2006, 8-week summer course to find details about the cognitive
activities of the students. [5]
The goals of this research were to understand how students are
learning and practicing design. The 12 students were given design journals with accompanying
guidelines modeled after Jain and Sobek’s to use during the mechanical engineering design
course.[4]
Encouragement for sketching was given to the students by was of a lecture on the use
of design journals and sketching. Using the McGown sketch level of detail the design journals
sketches were numbered and coded. The response was a scattered use of design journals by the
12 students involved in the course. Only 2 students showed ongoing use of the journals during
Page 14.1063.4
the design process which was seen during the concept generation and refinement stages. The
quality of the sketches included all levels except the highest level of McGown’s sketch coding
scheme which includes 3-dimensional drawings with dimensions and annotations. [11]
Sketches
from student journals that represent McGown levels 1 through 4 are included in Table 3. Even
with such limited use the authors conclude that sketching design journals provide much insight
into the student’s cognitive processes.
2.4 University of Maryland new coding scheme
Recognizing the need for a sketch-coding scheme that reflected more than artistic skills, a team
of researchers at Maryland developed a coding scheme for sketches in design journals and then
expanded that coding scheme to apply to any visual representation of any physical artifact
(Westmoreland et al., 2008). [7]
The scheme consists of attribute codes describing the subject of
the sketch (the subject matter – entire artifact or just a feature) and how the sketch is drawn (the
detail type). Examples of detail codes are motion arrows, dimensions, free body diagrams or
force vectors. The definition of the coding scheme and sample sketches can be found in Table 1
below. Incorporating type of detail and sketch subject matter into the coding schemes provides
more cues by which to infer the type of thinking that prompted the work. Coding these aspects of
the sketches provides a more focused framework for the analysis of the data than other sketch
coding schemes.
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Table 1: University of Maryland new coding scheme details
Code Description Sample Sketches From
Student Projects
Number Identify Report, Page number, visual number
A Type Number to indicate Sketch (1), Line Drawing (2), CAD
Drawing (3), Photograph (4), or Simulation Output (5)
B Design
Phase
Concept Generation
Embodiment Design
Detail Design
Redesign
Code: [A1,B2,C0,D2,E2,F2,
G0,H0,I0,J1,K0,L0,M1,N0]
C Sketch Lesson Indicator exists for courses in which a lesson is given to
students
D McGown Sketch Level sketch visuals are assigned a level according to
McGown’s coding scheme.
E Yang Sketch Level sketch visuals are assigned a skill level according to
Yang’s coding scheme.
Code: [A1,B1,C0,D2,E1,F3,
G0,H0,I0,J0,K0,L0,M0,N0]
F Subject
Matter
1-Entire artifact or subsystem
2-Exploded assembly
3-Artifact feature
4-Artifact in operation
5-Free body diagram
G Part of multiple objects code is for visuals that are in the same grouping on
a page but are very different from one another in type or subject
Code: [A1,B1,C0,D3,E3,F1,
G0,H1,I1,J1,K0,L0,M1,N0]
H Motion indicator code signals the presence of arrows or directional lines
that are show movement on a static plane of paper.
I Isometric view code is used for angled view
J Set of orthogonal views indicates the use of the standard mechanical
drawing convention of three orthogonal views of the same
K Part of set code signals a grouping of multiple visuals that are related to
each other (e.g. visuals coded for detail J would also be coded for K)
Code: [A1,B1,C0,D1,E1,F1,
G0,H0,I0,J0,K0,L0,M0,N0]
L Applied forces code is for visuals that are shown with force arrows. A
visual of type F5 would also code positive for detail L.
M Multiple views of one object is for related sketches, separated with
notations
N Dimensions code signals that one or more physical features are labeled
with size data.
Code: [A1,B1,C0,D2,E2,F1,
G0,H0,I0,J1,K0,L0,M1,N0]
Page 14.1063.6
3.0 Sketching Study Summaries
Three different studies were undertaken by the authors to build a research portfolio on the nature
of sketching in a mechanical engineering capstone design course at the University of Maryland.
Each study is briefly introduced here and the main results on the use of sketching are presented.
3.1 Sketches in Capstone Design Reports
Westmoreland, Schmidt, and Grenier studied the visual representations used by mechanical
design students in their Capstone Design Reports during in five semesters of (from) spring 2005
to fall 2007. [7]
These visual representations include sketches, CAD drawings, photographs, and
line drawings. This group includes N= 268 students and 49 reports (see Table 2: Sketch Data
from Final Report Study [7]
).
Table 2: Sketch Data from Final Report Study [7]
Semester # of Reports Avg. Grade Total # of Visuals Total # of Sketches
Spring 2005 5 90.5 96 1
Fall 2005 10 89.6 409 143
Spring 2006 8 88.9 161 61
Spring 2007 19 88.0 601 203
Fall 2007 7 87.0 230 83
Sketches made up 33.1% of the total number of visual representations of the artifact being
designed. McGown’s skill based coding scheme was applied and 77.9% of the sketches were
rated as level-1 and level-2 and there were no sketches in level-5. [11]
Yang and Cham’s coding
scheme produced a similar result; 82.9% were rated as level-1 and level-2 and none were rated in
the highest level. [12]
Additional statistical analysis was done on the 33 reports in spring 2006, spring 2007, and fall
2007 (this subset was found to be most homogeneous with respect to number of relative use of
sketches). [7]
The sketches were categorized according to the phase of the design process in
which they were created: 63.6% during concept generation, 10.8% during embodiment design,
and 25% during detail design. Pertinent findings can be summarized as:
1. Students will respond to the instructor requirements to sketch (and perhaps only to a
requirement to sketch).
2. Students use sketching as documentation of design most frequently during concept
generation and detailed design.
3. Skill-based sketch coding scheme reveal that the majority of students are creating low
skill and low complexity sketches.
3.2 Fall 2007 Paper Boat Project Sketch Coding for Skill and Complexity
Grenier’s work in part for her Master’s Degree in Mechanical Engineering requirements looked
at the conceptual understanding of sketching in the mechanical design process. A sketch
assignment (abbreviated SA) is included as regular design project homework in the Capstone
Page 14.1063.7
Design course at the University of Maryland. This assignment was created to improve
communication between the professor and the students during concept generation and to prepare
individual students for group design sessions. The assignment requires each student to generate a
small number of designs (four or five) and describe them with annotated sketches. Many students
wish to use CAD packages for this assignment and must be clearly exhorted to turn in hand-
drawn sketches. No specific requirements are given for the type of or number of sketches used to
explain each design concept. The requirement is only that a certain number of concepts are
generated and recorded. This assignment produces a large number of sketches for analysis.
During the fall semester of 2007 there were two sections of the capstone course, one traditionally
taught section (hereafter referred to as 472-1) and one experimental section (hereafter referred to
as 472-2). The course was operated with the same foundations as the standard sections of
capstone design. Section 2 (472-2) was an experimental section that emphasized prototyping,
idea logging, and sketching all the while working on their semester project. In addition, 472-2
students were given a Paper Boat design project during the first 2 weeks of the course. This
project was designed to prepare the students for the more detailed portion of the engineering
design project to follow in the latter part of the semester. The students used design journals
called “idealogs” to create conceptual designs of paper boats that they would like to materialize.
The students were given specific guidelines and goals for the paper boat from the instructor. The
Paper Boat Project was important for this study allowed the author to assess the sketching skill
level of the students at the start of the course.
Students in 472-2 were required to complete a sketching assignment on the Paper Boat Project.
In the Paper Boat Sketch Assignment, the 472-2 students were required to sketch four different
paper boat designs. Thirty-six of the enrolled students turned in a total of 459 sketches, 418 of
which were coded for this portion of the study. Descriptions of McGown’s sketch levels and
examples from the paper boat sketch assignment are found in Table 3. The middle column
includes sketches from a capstone design course held in the summer of 2006. [5]
Table 3:Illustrations of McGown’s Sketch Levels by Grenier [2]
McGown’s Sketch
Level
Sketch Sample from UMD Study in
Summer 2006 [5]
Sketch Sample from 472-2 Paper Boat
Sketch Assignment
Level 1 sketches consist
of line drawings that
portray basic principles
without any details and
limited labels.
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McGown’s Sketch
Level
Sketch Sample from UMD Study in
Summer 2006 [5]
Sketch Sample from 472-2 Paper Boat
Sketch Assignment
Level 2 sketches show a
concept’s working
principles without
product form details,
but may include brief
annotations.
Level 3 sketches display
product form and may
contain shading and
brief annotations.
Level 4 sketches show
product form with
annotations,
illustrations of features
and detail, and may
include dimensions.
The Paper Boat Sketch Assignments (418 sketches) were labeled and coded independently by
two graduate students, hereafter called R1 and R2. The McGown and Yang sketch coding
schemes were used. These two coding schemes are subjective. Grenier did a coder reliability
study using the Paper Boat Sketch Assignment. The Pearson correlation coefficient was
calculated to evaluate the correlations between R1 and R2 Paper Boat Sketch Assignment
coding. The Pearson correlation determines to what extent the relationship between two random
variables are linear, and, therefore correlated instead of random. R1’s and R2’s correlation on
the coding of McGown level sketches is statistically significant (p-value = 0.048). R1’s and
R2’s correlation on the coding Yang level sketches is also statistically significant (p-value =
0.006). The relationships between R1 and R2 coding with McGown and Yang sketch coding
schemes are strong, 0.881 and 0.972 respectively.
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The results of the coding indicate that the vast majority of the 418 sketches were coded in the
lowest 2 levels of both sketch-coding schemes. The average number of sketches in level 1 for
McGown’s coding scheme was 145.5 and the average numbers of sketches in level 1 for Yang’s
coding scheme were 327. The average number of sketches in level 2 for McGown’s coding
scheme was 254 and the average numbers of sketches in level 2 for Yang’s coding scheme were
76.
These observations follow the analysis of the Paper Boat Sketch Assignment.
1. The McGown and Yang sketch coding schemes were applied with reasonably high
reliability between coders.
2. The vast majority of the sketches submitted for the Paper Boat sketch assignment were
low quality sketchers.
3. All of the student teams in 472-2 completed the Paper Boat project regardless of their
sketching performance.
Therefore, to the extent that sketches were useful in the Paper Boat design project, the McGown
and Yang sketch coding schemes did not recognize all of the valuable elements of the sketches.
3.3 Comparison of Sketching Assignments Before and After Sketching Importance Lesson
During the fall 2007 semester, 472-1 students performed one sketch assignment (SA) on their
main semester project; this assignment is referred to as 472-1SA. There were two sketch
assignments required from students in 472-2. The first sketching assignment was on the Paper
Boat Project described in the previous section; it's referred to as 472-2PB. The second sketching
assignment, 472-2 SA, was given after a 45 minute sketching importance lesson. Students were
given the same assignment as the 472-2 Paper Boat sketch assignment; the only difference was
that the topic of their sketches was on the main semester-long design project. The only difference
in the wording of the assignments is that students in 472-2 were required to generate and
describe four concepts in each of their assignments. Students in 472-1 were required to describe
5 concepts.
A sketching importance lesson was given to students of 472-2 between their two sketching
assignments (i.e., 472-2PB and 472-2 SA). The sketching importance lesson focused on the
value of sketching for design not on how to sketch. Elements of the sketch lesson included 6
PowerPoint slides and 1 article handout.
The sketching importance lesson plan is as follows:
1. The importance of sketching: 3 slides were spent on the describing the Romer study and its
results. [16]
In the Romer study 45 mechanical engineering students were given a design
problem to solve. The students were divided into three groups: (1) unlimited use of self made
sketches throughout the process (2) use of self made sketches part way through the design
process and (3) no sketching allowed. The results were that groups 2 and 3 performed more
quickly than group 1. Group 1 (unlimited sketchers) found the problem to be significantly
less difficult than group 3 (no sketching allowed). There was no significant difference in
certainly of the correctness of the solution. Participants stated that sketching was an aid for
Page 14.1063.10
Sketching vs. CAD
Ambiguous
Open Ended
Hand on Paper
Unlimited
Good for Concept Generation
Communication tool
Memory-relieving
function
Tangible
Exact
Computer Mouse Use
Limited by knowledge of CAD program
Good for Final Design
Figure 1: Sketching uses vs. CAD
uses
analysis, short term memory, communication,
and documentation. Sketching helped students
develop, test, and improve their solutions.
Nevertheless, two-thirds of the subjects agreed
that the design problem could be solved
without sketches.
2. There was a discussion covering the value of
sketching in communication and as a meta-
cognitive tool.
3. There was a discussion of the uses of
sketching versus CAD drawings as shown in
Figure 1: Sketching uses vs. CAD uses.
4. Students were given the short article by author
McCormick on the benefits of sketching; the article was titled “Seeing Mechanical”. [3]
A
brief discussion of the article is facilitated by the instructor.
The sketching assignments were collected and coded using the new coding scheme. The results
found were dramatic.
Table 4: ANOVA Number of Sketches Submitted per team per assignment
Percentage over Teams
472-1SA 472-2PB 472-2SA ANOVA Results
Number of Teams 7 Teams 9 Teams 8 Teams F-Value p-value Differences
Sketches/Member 10.276 13.259 6.169 11.31 0 Significant
First, the number of sketches completed differed as indicated in Table 4.There was a significant
decrease in the number of sketches submitted by students of 472-2 when asked to sketch
concepts for their design projects. The difference is more than can be accounted for by just the
difference in required minimum concept number. (472-1SA required sketches for five concepts
while the 472-2 assignments required sketches for four concepts) The 472-2PB sketch average
per team member for 4 sketches is actually higher than that for 472-1SA. The same students
sketching paper boat designs at an average of 13.259 each reduced their average to 6.169 for
their project SA, and the paper boat design was much simpler than their semester project. The
only other factor that could explain the change in 472-2 student sketching behavior is the
sketching importance lesson provided between assignments.
Table 5: ANOVA on Percentages of Sketch Level per team
Percentage over Teams
472-1SA 472-2PB 472-2SA ANOVA Results (N=23, α=05)
Number of Teams 7 Teams 9 Teams 8 Teams F-Value p-value
McGown Level 1 0.0318 0.2369 0.0085 11.41 0.000
McGown Level 2 0.8885 0.7091 0.6882 4.82 0.018
McGown Level 3 0.0725 0.0428 0.2401 14.71 0.000
McGown Level 4 0.0073 0.0111 0.0626 4.00 0.033
All ANOVA
Differences
were
significant
McGown Level 5 0 0 0 NA
Page 14.1063.11
Table 5 reports on ANOVA of the sketching skills between the sketching assignments. The
sketches were coded and the McGown level of each sketch was recorded. The number of
sketches at each level (1 to 5) was recorded for each team then divided by the number of students
on each team to normalize for differences in number of students. The final numbers were then
converted to percentages and averaged over the number of teams in SA group. Table 5 indicates
that there was an average of 23.7% of McGown Level 1 sketches in all the Paper Boat sketch
assignments from section 472-2. The average of McGown Level 1 sketches in their course
project sketching assignment was 3.2%.
The ANOVA on the percentage of McGown Level sketches per student per team showed
significant differences across sections regardless of the category. The table shows that 472-2
students submitted almost no Level 1 sketches for their project sketch assignment even though
they submitted 23.7% for the paper boat assignment. The same group of students submitted
about 24% of sketches at Level 4, far exceeding their use of this amount of detail in the paper
boat assignment and exceeding the Level 4 submission percentage of students in section 472-1. It
appears that the impact of the sketching importance assigment was to increase the amount of
detail and complexity that students included in their sketches. Coding the sketches with a
content-based coding scheme will reveal more detail about the changes in student sketch
behavior.
The sketches were analyzed using the content-based coding scheme described in Section 2.4.
This new coding scheme allows analysis of the subject matter depicted in each sketch and the
type of detail included. Results of ANOVA tests for sketch subject matter and possible content
detail type on sketches are shown in Tables 6 and 7. Table 6 displays analysis of the subject
matter choices.
Table 6: ANOVA on Percentage of Subject Matter per team
Percentage Sketches with Subject Matter
Averaged by Sketcher and then by Team
472-1SA 472-2PB 472-2SA ANOVA Results
Sketch Subject Matter
Codes
7 Teams 9 Teams 8 Teams F-Value p-value Differences
F1- Entire artifact or
subsystem
0.8927 0.8079 0.7082 1.04 0.37
F2- Exploded assembly 0.00977 0 0.04191 4.57 0.022 Significant
F3- Artifact feature 0.0641 0.0779 0.1679 1.99 0.161
F4- Artifact in operation 0.03342 0.0483 0.07801 2.26 0.129
F5- Free body diagram 0 0.01587 0.00391 1.03 0.374
Table 6 shows that the only significant difference between subject matter chosen for the sketches
is that of the exploded view of assembly. Teams in 472-2 increased their use of assembly
sketches over that of section 472-2 after the sketching importance lesson. The ANOVA was
conducted on average percentages of sketches per team per student to normalize out the
differences in number of students per team and the project tasks of the teams.
Page 14.1063.12
Table 7: ANOVA Comparison of Percentages on Type of Detail
Percentage Sketches that Included the
Detail Averaged by Sketcher and by Team
472-1SA 472-2PB 472-2SA ANOVA Results
Type of Detail 7 Teams 9 Teams 8 Teams F-Value p-value Differences
G Multiple Subjects 0 0 0.1126 3.44 0.051
H Motion Indicators 0.3245 0.04598 0.28753 19.36 0 Significant
I Isometric View 0.0106 0.0405 0.179 5.92 0.009 Significant
J Orthogonal Set 0.1578 0.1465 0.1874 0.08 0.926
K Part of a set 0.6503 0.4265 0.4669 2.34 0.121
L Applied Forces 0.02215 0.01825 0.04976 1.19 0.324
M Multi-views 0 0 0.14162 10.25 0.001 Significant
N Dimensions 0 0.1221 0.0692 2.7 0.09
O Notations 0.882 0.8717 Sketc
hin
g I
mp
ort
an
ce L
ess
on
0.9583 0.9 0.423
Table 7 reports ANOVA results on the percentages of sketches containing particular types of
details. Recall that column 472-1SA is a different section of students than the other two columns
and that the sketching importance lesson was given to students in section 472-2 in between their
Paper Boat Sketching Assignment (472-2PB) and their standard sketching design assignment on
their semester project (472-2SA).
The use of three types of details changes significantly when compared across the sketching
assignments.
1. Motion indications (detail H) are most frequent in 472-2SA. There is a significant difference
for the use of Motion indicators are used least frequently in the paper boat sketches; it is
likely that the paper boats were made without moving parts because of the design limitations.
2. Sketches drawn in an Isometric view (detail I) significantly increased in the students who
received the sketching importance lesson. Isometric (I) and orthogonal (J) views are used by
students in all three SAs. Isometric views (I) are less frequent than orthogonal views (J).
3. Sketches showing Multiple-views of one object (detail M) did not occur at all in 472-1SA or
472-2PB, but did occur in 472-2SA.
4.0 Summary of Findings
The findings reported in the studies show that students are will sketch if required by the course
instructor. There is overwhelming evidence that the sketching skills of the capstone design
students are poor when measured by skill-based criteria as used by the coding schemes of
McGown and Yang and Cham. These criteria include: the amount of detail in the sketch; the
complexity, the accuracy of representation; the consistency of the perspective displayed in the
sketch; and other skills of drawing. Nevertheless, the question of whether or not students’
sketching skills are adequate is open. The low quality of the sketches did not stop students from
progressing and succeeding in their projects.
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The low skill level displayed by students when sketching design concepts may account for part
of their reluctance to sketch. That is, few students consider themselves to be skilled sketchers.
This may explain students' desire to use CAD drawing programs even when given a "sketching"
assignment. It's also possible that students perceive CAD drawings as the more professional way
to represent alternatives. The irony is that the finished quality of CAD drawings is exactly the
wrong way to represent alternatives to designs at the idea generation stage. The ambiguity of
sketching is beneficial.
The content-based sketch coding scheme developed by the authors proved better at
discriminating among the sketches. The content of the sketches is easier to judge than the skill
level based on artistic qualities. The content-based coding scheme tracks the presence or absence
of cues such as motion and load arrows. This allows for better characterization of the type of
thinking that the sketcher was doing, beyond representing a concept. For example, motion arrows
on a sketch indicate that parts move relative to one another. Sketches showing a zoomed in view
of one area signifies emphasis on the feature being detailed.
A significant finding was that the sketching importance lesson changed the type of sketches
produced; the number of sketches produced by the students (a reduction), and increased the
number of details within sketches. The decrease in absolute number of sketches may be due to
the increase in the kinds of details in a sketch. It may be surprising that just talking about how
importuning sketching is to design has an impact on the sketching habits of students. Recall that
the sketching importance lesson also increased the percentage of McGown Level 2 and 3
sketches produced by the same students.
5.0 Future Work
The work presented here is just a glimpse into mechanical design research being done at the
University of Maryland. The use of sketching as a tool in engineering education is promising as a
means to peek into the designer's mind.
Encouragement for sketching is needed because students seem to be pre-wired to adopt the latest
technology in mechanical design tools to rather than sketching and miss out on its many benefits.
There are several barriers that exist in student’s minds about the role of sketching in the
mechanical design process. Many students feel in order to utilize this tool they must have some
type of formal training or schooling. In contrast, the many benefits from sketching are gained
using very elementary drawings and annotations that help the user create a working innovative
model. There are design practitioners that use sketching and drawing throughout their entire
process.
Future work can be done to dig into the attitudes students have about sketching during
mechanical design. Students are automatically inclined to use CAD instead of drawing hand-
sketches. Why is this? The value that sketching has during design is reflexively overlooked by
students, even when required to do hand-sketching assignments. More work is needed to
understand student unwillingness to sketch during design. A Concept Inventory on student
attitudes toward sketching has been piloted and results are under study.
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Studying sketching and other student behaviors during design remains a rich area of research
with many fascinating open questions.
Acknowledgements
The authors would like to thank the paper reviewers for their thoughtful and considered opinions
on the content of this paper and the structure of the research project. The authors are grateful for
the support and cooperation of University of Maryland’s Department of Mechanical Engineering
throughout this research project. Sophoria Westmoreland offers grateful thanks for funding given
by the National Science Foundation Louis Stokes Alliance for Minority Participation as well as
The Center for Minorities in Science and Engineering Office at The University of Maryland,
College Park. Any opinions, findings, and conclusions or recommendations expressed in this
material are those of the authors(s) and do not necessarily reflect the views of any other group or
institution.
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