ABSTRACT
Multimedia tutors have been developed for a number of different areas in manufacturing-including forging, die casting, and injection molding. Typically, students using these tutors perform better than students receiving traditional classroom instruction. However, the strengths and weaknesses of the tutors have not been isolated in any of the reports to date. This paper presents the results of experiments designed to isolate the most effective components used to teach design for stamping. The experiments compared classroom instruction with software tutorials. The results of these experiments indicate that the use of software tutorials when combined with feedback on graded homework assignments is as effective as traditional lectures that also make use of graded homework assignments
I. INTRODUCTION
In an effort to better educate students about manufacturing, students and faculty at the University of Massachusetts Amherst (UMass) have been developing interactive multimedia software tutorials for teaching design for manufacturing (DFM). The overall goals and objectives of the software tutorials (tutors) have been to enable students to identify difficult to create (expensive) features of a part, to assist them in visualizing the tooling required to create the part, and to provide them with the material that they need in order to learn with understanding. These tutors contain slowed down animations of the most important manufacturing processes used in the production of consumer products. They are designed to help students overcome some of the inherent difficulties encountered when viewing various manufacturing processes caused by the high speed of the processing equipment (stamping) and/or OSHA safety requirements.
To date four manufacturing software tutorials have been developed, namely, one each for design for injection molding [1-3], design for forging [2, 3], design for stamping [2, 3], and design for die casting. Formal and preliminary evaluative testing of the injection molding and forging tutors reveals that the tutors are approximately as effective as traditional lecture instruction. Numerous other comparisons have now been made of tutors and classroom instruction, almost all showing that tutors are generally more effective than classroom instruction [4-7]. However, the comparisons of various forms of tutor and classroom instruction that have been undertaken to date have failed to identify those factors that make instruction via one modality superior to instruction in other modalities. The overall goal of this research was to isolate the factors that made instruction in stamping most effective, both when that instruction was delivered in the classroom and when it was delivered using a multimedia tutor.
II. WHY MULTIMEDIA?
Multimedia tutoring systems have been shown to be highly effective with students [4-7]. Properly designed computer-based tutors have achieved the one-sigma effect [8], which is the same improvement in learning that results from one-on-one human tutoring over classroom instruction. That is, on average, students who learn using either computer-based tutors or one-on-one human tutoring perform at a level one standard deviation above the mean of students who learn using more traditional methods. Several success stories have described students learning in one-third to one-half the time it takes for a control group to learn the same material [9]. For example, undergraduate students using a Lisp tutor at Carnegie Mellon University [10] completed programming exercises in 30 percent less time than those receiving traditional classroom instruction did and scored 43 percent higher on the final exam. In another study, students working with an Air Force electronics troubleshooting tutor for only 20 hours gained a proficiency equivalent to that of trainees with 40 months (almost four years) of on-the-job training [6]. In a third study, students learned general scientific inquiry skills and principles of basic economics in one-half the time required by students in a classroom setting [9].
III. THE STAMPING TUTOR DEVELOPMENT TEAM
According to Bransford, Brown and Cocking [11], development of a successful tutor requires that the tutors:
* be based on an organized knowledge domain as an expert would organize it,
* be developed using an interdisciplinary software development team,
* contain a friendly and useable user interface,
* include clearly identifiable learning objectives, and
* have an introduction and a workshop.
To meet these requirements, the UMass team formed contained domain experts from engineering, and software and animation experts from computer science. The domain experts provided clearly identifiable learning objectives while the software experts were responsible for the development of a friendly and useable interface.
A. The Team's Domain Expertise
When asked to provide a cost estimate for the production of a special purpose part, a manufacturing vendor studies the drawing of the part and uses knowledge based on his or her extensive experience (i.e., what we will refer to here as conditionalizedknowledge) to retrieve the practical information needed to provide the estimate. In the case of a stamped sheet metal part, the expert visualizes the tooling required to produce the part and the potential difficulties presented by the choice of part material and sheet thickness.
In an effort to emulate the vendor's conditionalized knowledge, a knowledge acquisition phase was undertaken prior to development of the tutor. The approach used to acquire this domain expertise is described in [12]. The goal of the knowledge acquisition phase was to develop a group-technology based methodology [12] that could emulate the ability of an expert vendor to visualize the tooling required to produce the part and the potential difficulties presented by the choice of part geometry, part material and part thickness.
The methodologies developed and outlined in [12] and described in greater detail in, [13], among other places, formed the organized knowledge basis for the UMass tutors.
B. The Interdisciplinary Team
In addition to the engineering domain experts, who wrote the script and directed the production of the stamping tutor, animation and software experts were also part of the team. These experts were primarily faculty and students from the Computer Science Department. Their role was to produce high quality visually effective animations to illustrate the relationship between part geometry and the required tooling.
C. User Interface
The software domain experts on the tutor development team ensured that good color schemes and an agreeable layout with buttons and drop down menus were used and properly located. Comments provided by users of the various manufacturing tutors [1-3] indicate that a pleasant and easily navigable interface was used on each of the tutors.
D. Learning Objectives
The learning objectives of the UMass stamping tutor were to enable users to:
a) identify costly to produce parts,
b) suggest less costly to produce alternative designs,
c) visualize the tooling needed to produce these geometries, and d
d) learn with understanding.
E. Introduction and Workshop
The stamping tutor has both an introductory module and a workshop module. The introductory module provides the knowledge needed to understand the basic stamping process for individuals, such as students who may have no previous knowledge of the subject matter. The workshop module provides an opportunity for students to assess how well they have learned the elementary concepts explained in the introductory module. The tutor is designed so that one can go directly to the workshop module.
IV. THE SOFTWARE TUTORIAL
The actual design for stamping tutor, and in particular the introductory module and workshop module, need to be explained in more detail at this point in order to understand the evaluations of the tutor that we want to describe later in this paper.
A. Introductory Module
In the introductory module, the user is introduced to stamping via a series of screens that contain text, animations, and voice-overs. The emphasis in this module is to make the user aware of the relationship between the shape of a part (part geometry) and the ease or difficulty of constructing the dies (tooling) required to produce the part.
