Jack, H., “Teaching Basic Mechanics Using Computers”, ICEE Conference Proceedings, Chicago, August 1997.

TEACHING BASIC MECHANICS USING COMPUTERS

 

Hugh Jack*, Assistant Professor, Padnos School of Engineering, Grand Valley State University, 301 West Fulton St., Suite 618, Grand Rapids, MI, 49504, phone: (616)771-6755, fax: (616)771-6642, email: jackh@gvsu.edu

 

 

ABSTRACT

 

Using the Internet, and recently developed software packages it is possible to use computers in the classroom to effectively teach basic mechanics. The author has been using the Internet and software packages called Working Model and Mathcad to present materials and simulations in lectures. This has lead to a very effective form of presentation that is not possible with traditional media such as overheads.

 

This paper will take the form of a discussion of both a statics and a kinematics course based on these tools. The topics to be covered will include technical hurdles to overcome, anecdotes of note, and some strategies for enhanced teaching. The objective of the paper is to help other faculty members thinking of using computers in the classroom.

 

 

INTRODUCTION

 

Computers in the classroom are little more than glorified overheads - when all we do is use computers and data projectors to replace transparencies. Computer based overheads (notes) provide more appealing graphics, without the disorganization of transparencies. The computer based notes can then become a framework for multimedia and simulations.

 

I have been incorporating computer use into my lectures over the last year. Originally the lectures were presented using word processing software (Framemaker). The lecture materials were then converted to Web documents on the Internet, in HyperText Markup Language (HTML). These notes were presented in class with the Netscape browser and an Internet connection. The HTML format allowed the addition of other media, such as digital photographs (JPEGs), physical simulations in Working Model, and small movies clips(MPEGs). The Web site was expanded to include general information for students, such as problems to do in the textbook. More recently I gave students web pages that are used to submit homework, and retrieve the marked results.

 

In other papers I have discussed many of the details of using computers to present [1] and to prepare course notes for the Internet [2]. In this paper I would like to discuss details of two course that have been run using these technologies. The first course is EGR209 - Statics and Solid Mechanics, the second course is EGR 352 - Kinematics and Dynamics of Machines.

 

EGR 209 - STATICS AND SOLID MECHANICS

 

A bit of background clarifies how I came to use computers in lectures. Before I started at GVSU in the fall of 1996, I had taught statics to over 500 students using traditional blackboard/overhead presentation methods. When I started my previous position lecture sizes were approximately 50 students. In my third year there, the lecture sizes has swollen to 200 students. This made it impossible to use traditional blackboard methods. This forced me to use overheads to lecture, but the level of detail possible with overheads and markers was poor. As a result I produced a formal set of notes that the students would bring to the lecture with them. This changed the strategy of the lecture from material delivery to value added. The students would add notes, or solve parts of problems on the lecture notes themselves. I observed that this value added approach to lectures helped in my organization, and changed the role of the student from dictating notes, to comprehension of material. This also meant that I had a complete (and debugged) set of course notes on computer!

 

The Notes

 

In my first term at GVSU I was asked to teach the Statics and Solid Mechanics course. This allowed my previously developed Statics note set to be reused, with the additional solid mechanics topics. Before the term began I filled in the course notes and sent them to the bookstore for reproduction. I had the notes reproduced on a single side only so that students could add notes on the backs of the pages. I had also prepared a number of problems to be done during the lectures with spaces for the solutions. On the first day of classes the students were asked to buy the notes, and bring them to every lecture. For the first few weeks of the term Framemaker was use to present the lecture notes, this eventually switch to Netscape and HTML.

 

Towards the end of the term I prepared and handed out supplements to the noteset, based on student feedback that I had received. In general the students liked the notesets, but they did request additional worked problems to help reinforce methods and build confidence.

 

The Lectures

 

A notebook computer was used to present lecture material. This required a separate data projector. These projectors were available in closets in the hall with no formal control system. As a result access and availability was a problem at times. This also required a few minutes to retrieve and return the projectors. At other times these projectors had been used by others who left unusual settings that were hard to correct. On a few occasions that term I had to conduct the lecture using the blackboard. This was not a large problem, but did seem to throw off the lecture style.

 

During the lectures I found a few small problems. The data projector left the room quite dark, except for the screen. As a result many students became lethargic when left in the dark too long. As a result I developed a habit of running the lecture for a few minutes, and then finding an excuse to turn on the lights and draw a figure or solve a problem. Inadvertently this rhythm kept the students more involved. When it was not possible to turn on the lights I would circulate and ask questions to stimulate the drowsy.

 

The general flow of the course seemed to arise from the topic sequence. Statics is well suited to topical modules. For each module the general sequence was,

1. Present material for a new topic with discussion elements and practical examples. This would often make use of the computer to present lecture notes, photographs, and simulations with Working Model. (see figure 1 for an example)

2. Present a simple example problem and solution.

3. Turn on the lights and have the students try solving a simple problem (in a blank space in the notes).

4. Present a complex problem in the notes.

5. Turn on the lights and have the students try a more complex problem in the notes.

6. Present another example in the notes, and conclude the topics.

7. Suggest problems to try in the notes.

8. In this or a later class solicit outstanding problems in the text. At this time Working model can be used to illustrate some difficult concepts.

 

At the end of the course the general response to computer based presentations was positive. The printed noteset, combined with the computer projection reduced student dictation, and increased the time to think. This also reduced the time normally spent facing the board and writing. Some of the media had a strong impact on the students. In particular the friction section was well comprehended because of Working Model examples of slip and tip. Many students found photographs of actual trusses useful in comprehension.

 

Figure 1 - Working Model Screen Capture

 

Student Use Of Software

 

I was somewhat conservative in requirements. In the first month of class I handed out a tutorial guide for Working Model, and encouraged students to try it in the laboratory machines. At that time a simple planar equilibrium problem was assigned that was to be solved by hand, with bonus marks for verification using Working Model. The result was a number of submissions of reasonable quality. A competition was then run with the objective to make the most appealing Working Model demonstration. This was judged by the students in the class, and the results here were very exciting. The results for this contest, and the entries were all posted on the Web site for the course.

 

All of the students in the course had been required to learn Mathcad in a previous course. Later in the term I assigned a ‘big picture’ project that involved the analysis of various exercise machines. The students were expected to measure dimensions, estimate forces externally, calculate internal forces, and estimate deflections and factors of safety. The analysis was to be done and submitted on Mathcad (see figure 2). The final results from these projects were also added to the course website.

 

Figure 2 - MatchCAD Screen Capture

 

The Web Site

 

The Web site for the course [3] was the glue that held all resources together. When the site was created in the third week of class it held only course notes. The notes were converted from Framemaker format to HTML using webmaker and webworks software. Both have significant bugs, but they can be made to produce reasonable quality web documents. In both cases a set of rules are created to convert paragraph styles in the document to web styles. The notes were cut into smaller files to reduce the download times in lectures, and over phone lines. The web site was updated throughout the term by adding and linking subdirectories. Items that were added were,

• JPEG digital photographs (approximately 100 @ 100Kbytes)

• MPEG of Tacoma Narrows Bridge (1 @ 1Mbyte)

• Working Model files (approx. 50 @ 10Kbytes to 200 Kbytes)

• notes in HTML and GIF (hundreds of files approx. 5Mbytes in size)

• Student Mathcad files (20 @ 100Kbytes)

 

As material was covered homework problems were posted on-line. This allowed students to get these problems from any location. Although this exposed some access problems on campus. One time before an exam the network was down for a day, and this resulted in some tension. After midterms solutions were posted to the Web, allowing students to walk out of the exam room and check their solutions immediately. I had one student who came to my office within minutes of writing the test to ask a question about the solution.

 

The students in this course were sophomores, with different levels of computer experience. Some of the students were very enthusiastic to use the Internet to access course resources. But there was a reluctant group (<10%) of the class that had a strong dislike of computers. This trend disappears in the junior and senior classes.

 

EGR 352 - KINEMATICS AND DYNAMICS OF MACHINES

 

This course covers the topics of linkages, gears, cams, robotics and multibody dynamics. New course materials were developed and put on the web. The focus of the course was changed to computational methods, previously the course focused on drafting techniques. This called for the use of Mathcad, Working Model and Autocad.

 

The Notes

 

The notes were developed to parallel the textbook, and put on the web. This process was similar to that used in the Statics course, except the course began with the notes on the Web site. The students were also asked to bring the course notes to the lectures.

 

The Lectures

 

The lecture format was also similar to Statics, using the notebook computer, and data projector. The lectures use a combination of presentation and worked problems to keep up student interest.

 

Student Use Of Software and Web

 

Unlike statics, this course places much more emphasis on software usage. On this first day of class the students were,

• given the address (URL) for the web site

• given a tutorial guide for Working Model

• told that Mathcad and Autocad usage is required

• given computer accounts with a sample Web page

• a simple assignment to force Working Model and Web usage

 

Throughout the term the students did a number of assignments using software (see figure 3). For basic linkages these assignments used Working Model to show positions/paths, velocities, and accelerations. Cams and Gears were designed using Mathcad or Excel to generate geometries, and Autocad to constructed drawings. Working model was then used to verify the designs. Mathcad was used to deal with the matrices found in the robotics section. Finally, Working Model was used to model the dynamics for internal combustion engines.

 

Figure 3 - Analysis of a Four Bar Linkage in Working Model

 

Marking On-line

 

To submit assignments, students would add the appropriate files to their home pages. In some cases the results are exceptional. These finished assignments are then available for general viewing. The marking process typically involves,

1. go to the students home page.

2. find the particular assignment to be marked.

3. select the file of interest. If this is a working model file, it will be downloaded, and the Working Model program will execute.

4. The file is examined for technical detail, comments and a grade are added in red text.

5. The file is saved, and copied to the students directory

6. The mark is recorded in a spreadsheet program.

To do marking in this form it is necessary for the faculty member to be able to write to the students directory. In addition the directory where the marked materials are left must not be readable by other students. For my web site I used a Linux machine, and did marking as ‘root’. This method was very convenient, and the results of the student work was unambiguous as far as the calculations and models are concerned.

 

The Web Site

 

Each student had an account set up. In their main directory there is a subdirectory ‘public_html’ for their ‘HTML’ pages. There is another directory called ‘marked’ that can only be read by root and the student for returning marked work. The students maintained their own directories and web pages during the term. To update web pages many used a browser such as Netscape Gold, or ‘Microsoft Word documents saved as HTML.

 

CONCLUSIONS

 

The two courses described in this paper outline many of the issues that arise when using computers to teach mechanics courses. This included software, hardware and strategic discussions. Others considering such ventures may want to look at the course materials, and student pages on-line [3]. Based on previous experiences the author plans to expand the use of computers to teach basic mechanics, as well as other courses.

 

 

REFERENCES/BIBLIOGRAPHY

 

[1] Jack, H., “Use of Computer Technology in the Classroom”, ASEE National Conference, Milwaukee, June, 1997.

[2] Jack, H., “Developing Multimedia Courseware for the Web”, ASEE North Central Section Conference, Dayton, Ohio, April, 1997.

[3] http://claymore.engineer.gvsu.edu

[4] Sears, A.L., “A Multimedia Manual on the World Wid Web for Telecommunications Equipment”, IEEE Transactions on Education, Vol. 39, No. 3, August 1996, pp. 342-348.

 

 

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