Sketching During Mechanical Design: Studying Sketching At ... · The University of Maryland,...

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AC 2009-1570: SKETCHING DURING MECHANICAL DESIGN: STUDYING SKETCHING AT THE UNIVERSITY OF MARYLAND Sophoria Westmoreland , University of Maryland Sophoria Westmoreland is a Graduate Student at the University of Maryland in the Department of Mechanical Engineering. She completed her first bachelor's degree in General Engineering at Clark Atlanta University and her second bachelor's degree in Mechanical Engineering at Georgia Institute of Technology. Ashley Grenier, University of Maryland Ashley Grenier is an May 2008 Master's graduate from the University of Maryland in the Department of Mechanical Engineering. Linda Schmidt, University of Maryland Linda C. Schmidt is an Associate Professor at the University of Maryland in the Department of Mechanical Engineering. She completed her doctorate in Mechanical Engineering at Carnegie Mellon University and developed a grammar-based, generate and optimize approach to mechanical design. The dissertation title was "An Implementation Using Grammars of an Abstraction-Based Model of Mechanical Design for Design Optimization and Design Space Characterization." Her B.S. and M.S. degrees were granted by Iowa State University for work in Industrial Engineering with a specialization in queuing theory, the theory of waiting in lines. Her research interests include computational design, design optimization, and developing formal methods for design. Her educational interests include the development of student project team training 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 of Engineering Education. © American Society for Engineering Education, 2009 Page 14.1063.1

Transcript of Sketching During Mechanical Design: Studying Sketching At ... · The University of Maryland,...

Page 1: Sketching During Mechanical Design: Studying Sketching At ... · The University of Maryland, College Park in the Department of Mechanical Engine ering. Student sketching skills were

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

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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]

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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

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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

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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

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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.

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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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