|Teaching and Learning Forum 2000 [ Proceedings Contents ]
Physics for hands on units in Computing Science
David Veal and Stanislaw Paul Maj
Department of Computer Science
Geoff I. Swan
Edith Cowan University
Computer Installation and Maintenance (CIM) and Network Installation and Maintenance (NIM) are two new single semester units designed and implemented at Edith Cowan University (ECU). Both attract students from a wide range of disciplines and also cross-institutional enrollments from other universities within Western Australia. Significantly these new units have a substantial "hands on" component consisting of a workshop and associated lecture, both of 2 hours duration, on a weekly basis.
A detailed analysis of students via tests clearly demonstrated that many did not have sufficient background knowledge of physics to fully support their learning. Electrical theory concepts were of particular concern. Test results tended to cluster about two regions, one region represented the group with little or no physics background, the other region represented those who had studied the subject at or above upper high school or had worked in the electrical or electronic trades. In the units CIM and NIM students are required to work in a potentially hazardous environment and a knowledge of basic physics is essential to appreciate certain Safety & Health principles. Furthermore some students also experienced difficulties with mathematics in the area of formula derivation, manipulation and substitution.
The importance of a basic knowledge of physics as a foundation for understanding technology is discussed and potential methods of underpinning such understandings are considered.
Rapid changes in computer and network technology have resulted in low cost network PCs that now dominate in commerce and industry and are a common feature in many households. This equipment is typically maintained by first line maintenance, i.e. module replacement. Furthermore students from other disciplines now require courses in computer technology appropriate to their needs, e.g. in the fields of e-commerce and multimedia as described by Maj, Kohli and Veal (1999). The units (Computer Installation and Maintenance (CIM) and Network Installation and Maintenance (NIM) have been introduced at Edith Cowan University (ECU) and have been running successfully for a number of years. These units were designed to form the basis of a new curriculum for computer and network technology based on a market analysis of employer expectations. The CIM curriculum has been extensively evaluated and is always oversubscribed, has a low attrition rate (< 10%), attracts students from a wide range of disciplines as well as cross-institutional enrollments from other universities within the Perth area.
Research at both at ECU as well as two other European universities indicated that most of the computer science participating graduates lacked a sufficient background, both with respect to skills and the knowledge, required by prospective employers in computer and network support An independent evaluation of the unit CIM found that 80% of students would recommend this unit; 75% found the practical sessions useful; 70%; found the unit relevant to their needs; and 55% think it should be a compulsory unit. One part-time student who successfully completed this unit and is now working in Computer and Network Support wrote:
The material faced during CIM was exactly like a real live situation, which I guess was the desired aim, and this was extremely beneficial. (Maj Robins Shaw and Duley, 1997).
Havard has noted that many students may not be aware of the needs of industry in their field of study.
On completion of their academic programme the graduate was given no way of knowing how their skills compared to the requirements of industry. (Havard Hughes and Clarke, 1998).
The units CIM and NIM have also been offered on a full fee commercial basis. Both are designed to provide students with the theoretical foundations and associated practical skills relevant in the market place. In such fast developing fields unit content requires frequent updating. Employer expectations were determined via a market analysis of a range of industrial and commercial companies. Accordingly a dedicated laboratory was commissioned.
The workshops are based on IBM compatible machines. Each two hour workshop consists of a set of tasks for the student to undertake and all students undertake the same set of tasks in a given workshop. The workshops are designed to be integrated with an associated lecture also of two hours duration. Both units are designed to integrate practical exercises (Procedural knowledge) with a theoretical understanding (Declarative knowledge) gained through lectures. According to Cervero:
Declarative knowledge is knowledge that something is the case; procedural knowledge is knowledge how to do something'. 'Both declarative and procedural knowledge are essential for professional practice. (Cervero, 1992) cited in (Maj et al, 1997).
Ryle has stated that:
Theorists have been preoccupied with the task of investigating the nature, the source, and the credentials of theories that we adopt that we have for the most part ignored the question what it is for someone to know how to perform tasks. In ordinary life, on the contrary, as well as in the special business of teaching , we are much more concerned with people's competencies than with their cognitive repertoires, with the operations than with the truths that they learn. (Ryle, 1949).
CIM unit workshops require students to install and test a range of components. As an example of some of these workshops are shown below:
CIM theoretical knowledge includes, although is not restricted to:
- Power supply unit testing;
- Basic fault finding exercises using PCs.
- Master-slave hard disk drive;
- CD-ROM installation;
The NIM unit assumes basic skills and understanding developed during the CIM unit. A knowledge of the characteristics of the various cabling used and sources of potential electrical and electromagnetic interference is required. Furthermore, students in the NIM unit have the opportunity to design, install and test a small Local Area Network (LAN). This includes establishing a file server, client, the construction and testing of cabling.
- The operation of power supply units
- Monitor operation and standards.
- A comparison of PC buses.
- The operation of CD-ROM drives.
- Hard and floppy disk drives,
Uniquely these curricula has extensive workshop exercises that require students to work on equipment they are likely to meet in the workplace. It should also be noted that for one of these units (CIM) the workshop environment is potentially hazardous to students.The lecturer and tutors on the CIM unit noted that there was a problem with many student's understanding of basic electrical theory. The students come from a wide range of academic and technical background. Some students came to the unit from arts based faculties.
Physics concepts required on the CIM unit
Concepts are Current flow, Voltage resistance and power. The term voltage can be problematic and Arons has noted that:
the widely used term voltage generates more confusion than enlightenment. The word is used by different authors in different contexts, and no clear systematic operational meaning has crystallised. The result of this variability is to blur for many students The result is to blur, for many students the distinction between emf, and potential difference. (Arons, 1997).
The mentioning of Extremely High Tension (EHT) as is necessary for practical and safety reasons can only serve to increase such confusion.
The follow concepts are also required:
- The problems of translating very basic circuit diagrams as used in simple calculations to low power connections within the PC may also be problematic for many students. The importance of maintaining good electrical connections, Dry joints, and the fact that circuit elements in parallel receive the same voltage needs to be understood. The fact that integrated circuits require an electrical power source are also of importance The first author noted upon question more than one occasion a student did not realise that integrated circuits require a voltage to be applied to them to provide electrical power for their operation.
- The ability of capacitors to store charge is also required as is the fact that electrostatic discharge can damage integrated circuits.
- Magnetism, electromagnetism, induced magnetism, deflection and focus of electron beams.
- Transformer action.
- Colour mixing. Light emission from substance when impacted by high speed electrons.
- AC, DC and rectification.
- Physics based calculations required on the CIM unit include Ohm's law, Power, Frequency to time-period conversions and hence Bytes per second and hence throughput calculations, scientific notation and SI magnitudes.
Basic physics (electrical knowledge) questionnaire
At the start of a CIM unit students were given the option of answering a questionnaire which also included a short test and more than 50% of the students (48) agreed to participate. The students were asked a range of questions based upon on electrical theory and the questionnaire also inquired about their background in physics and electrical knowledge and practical experience.
The CIM group investigated came from a very wide range of physics backgrounds from a degree in physics to year 8 and also a wide range of backgrounds with regard to practical electricity and electronics form no background or previous experience to an electrician with many years experience. Test results tended to cluster about two regions, one region represented the group with little or no physics background, the other region represented those who had studied the subject at or above upper high school or had worked in the electrical or electronic trades.
Only 32% of the participating students managed to correctly draw a voltage and current measuring circuit using an ammeter and voltmeter. However, 68% could at least determine current flow direction given a range of alternatives. Given a battery and globe, (Light bulb), most of the students could not calculate the current flow or the power consumption.
The Throughput Questionnaire
It was also noted that students experienced difficulty with calculations required to calculate throughput both in assignments and end of semester examinations. The questions asked by some students indicated that they had difficulty with:
Potential solutions include the following:
- the manipulation of equations
- SI units and scientific notation
- concepts of frequency, throughput in bytes per second and periodic time and conversions between these quantities.
Basic physics to be taught via computing workshops using the PC as an example
As the unit extensively refers to PCs, teaching the required physics in context via the use of PCs could be a particularly attractive idea. Workshop exercises using a digital multimeter to measure voltages and continuity have been developed. This is an "in context" approach with no extra laboratories required as workshops containing sets of PCs are already extensively used in the CIM unit. Furthermore this "hands on" approach is in accordance with the basic philosophy of the CIM unit and could therefore be incorporated into its workshops. With this type of "knowing how" exercise it was felt that Competence Based Assessment (CBA) was appropriate to ensure that students could successfully use the equipment in an effective practical manner. Subsequently such a CBA has been developed, see Appendix B. The development and testing of CBAs on the CIM unit has been discussed by Veal, Maj, Fatherston and Kohli (1999).
Competency has been defined as "The ability to perform in the workplace" by (Goldsworthy, 1993).
Karmel has stated that:
The competency movement that has developed in Australian education over the last five or six years has been driven largely by a desire to fashion and improve education/training outcomes in relation to the world of work from entry to professional level. The origins of competency based training, standards and assessment for specific skilled vocations are also to be found in moves to reform industrial awards. (Karmel, 1995).
Whilst Weightman observes that:
Getting action attached to the titles and lists of competency is the issue. Just developing a list of appropriate competencies and assessing the required ones will do little or nothing to improve the performance of individuals or the organisation. (Weightman, 1994).
Such CBAs can be used by staff to check student understanding and skills.
In utilising PC Hardware to aid understanding of the basics physics required on these units there is a potential problem that the added complexity of the internals of a PC may overwhelm some students. This could also make basic physics principles more difficult for students to comprehend than might have occurred via a more conventional laboratory approach. Simple "hands on" examples of basic physics principles using standard physics laboratory equipment could be used by the students before they investigate actual devices in the PC.
More drill and practice
This could allow more time to reinforce basic concepts and to enable more practice with formula manipulation. However this may detract from time available in lectures and workshops and many students may not require this extra work. But such work could be optional and undertaken outside of normal lectures and workshops via the use of distance learning material. The development of such material may well require the investment of much time, effort and thought for it to be successful.
A short physics course
Such a course would only need be undertaken only by those requiring it and the emphasis could be entirely on the physics and associated calculations required for the CIM unit. However most students (67%) did not require this option when specifically asked on the questionnaire. Upon informal inquiry amongst the students it was found that some thought that they possessed a sufficiently good knowledge of physics for the CIM Unit. Whilst others felt that they did not have the time for and additional short course. However, many did not want, or could not afford, any extra expense involved with their studies.
Multiple choice questions (MCQs)
These can be used to expose misunderstandings and hence allow discussion and further questions explanation. A series of such tests have been developed by for the CIM unit and a selection with their purpose is noted in Appendix A. The first author has made extensive use of such techniques whilst teaching university entrance physics in the UK.
MCQs can be used to check across a broad area of student understanding, including calculations, within a relatively short time span and without the need for excessive writing on the part of students. Self marking can be undertaken by students as these questions are not being used for assessment purposes. With such techniques incorrect answers may be as important, if not more important, than correct answers as incorrect answers in such a situation may help to give a window into understanding student misconceptions. Scouler notes that different forms of assessment can encourage different forms of learning. (Scouler, 1998).
However, correct answers may only indicate correct guessing which may not be based on understanding. However when the reasons for the answers are given to the student misunderstandings may still be rectified. Multi-choice questions could encourage the learning of cues rather than an understanding of the subject matter. Heywood presents an analysis of the effectiveness of multi choice questions. (Heywood, 1989). Whilst Farthing notes the use of permutational multi-choice questions where a sequence of correct answers are required to score in an attempt minimise guessing effects. (Farthing Jones and McPhee, 1998)
Choosing a method of approach
Each of the above possible methods has advantages and disadvantages although they are by no means mutually exclusive. It is intended to trial the above approaches to attempt determine which optimum approach or mixture of approaches is the most effective.
Many other possible methods for overcoming the problem of teaching basic physics are possible. One such attempt is solving physics problems via a networked computer and an audio link as described by (Whitlock. Scanlon and Taylor, 1999).
An important reason for a encouraging an understanding of basic physics on the units is that this could help to bring about a better appreciation of hazard awareness. Safety and Health aspects include the following topics. Note that this list is by no means exhaustive.
- The effects of electrical current flow through the body causing muscular contraction and possibly making it impossible to release the object passing current into the body. Yet another is the effect of sudden powerful muscular contraction in making it sometimes possible for people to be thrown some distance with certain electrical shocks.
- The importance of Earth or Ground Current Leakage Detectors and their basic operation.
- An awareness of the danger of stored charge in capacitors.
- An understanding of the possibility of severe electric shock from EHT even though a person may not actually touching the object at EHT potential.
- The heating effect of an electrical current particularly in the case of short circuits causing melting of PVC coverings and the importance of not touching them in a misguided attempt to avoid further damage.
- An awareness of the danger of implosion of vacuum tubes used in desktop monitors.
In the not too distant past a certain background knowledge could have been assumed in higher educational institutions and now this is not necessarily the case. The success of the CIM and NIM units in attracting many students from such diverse levels of technical backgrounds has brought with it the problem of many students not possess a sufficient background in physics to facilitate learning in certain areas. A flexible response is now required in many situations and this paper has outlined some of the investigations and potential solutions that are part of such a response. The background knowledge required on these units reinforce the fact that physics, being at the basis of many modern technological devices, is a subject that is difficult to avoid.
A basic understanding of physic principles could also have safety and health implications. Furthermore understanding of physics is also important to enable students on the CIM and NIM units to appreciate present and future hardware developments.
Arons, A. B. (1997). Teaching Introductory Physics. John Wiley and Sons Inc, New York. 204.
Cervero, R. M. (1992). Professional practice, learning and continuing education: An integrated perspective. International Journal of Lifelong Education, 11(2).
Farthing, D. W. Jones, D. M. and McPhee, D. (1998). Permutational Multi-Choice Questions: An Objective and Efficient Alternative to Essay-Type Examination Questions. ITiCSE Dublin Ireland. 81-85.
Goldsworthy, A. W. (1993). IT and the Competency Debate - Skill vs Knowledge A Major Issue. The Australian Computer Journal, 25(1).
Havard, M. Hughes, M. Clarke, J (1998). The Introduction and Evaluation of Key Skills in Undergraduate Courses. Journal of Further and Higher Education. (NATFHE, Abingdon, UK), 22(1). 61-68.
Heyward, J. (1989). Assessment in Higher Education. 2ed. John Wiley & Sons. Chichester. 222- 225.
Karmel, P. (1995). Education and the Economic Paradigm in Confusion Worse Confounded - Australian Education in the 1990s. Academy of the Social Sciences in Australia. Occasional Paper Series,1.
Maj, S. P., Robins G., Shaw, D. and Duley, K. W. (1997). Computer and Network Installation, Maintenance, and Management - A Proposed New Curriculum for Undergraduates and Postgraduates. The Australian Computer Journal, 30(3).
Maj, S. P., Kohli, G. & Veal, D. (1999). Teaching Computer and Network Technology to Multimedia students - a novel approach. Paper presented at the 3rd Baltic Region Seminar on Engineering Education, Goteborg, Sweden.
Maj, S. P., Fetherstone, T., Charlesworth, P. and Robbins, G. (1998). Computer and Network Infrastructure Design, Installation, Maintenance and Management - a proposed new competency based curriculum. Proceedings of the Third Australasian Conference on Computer Science Education, The University of Queensland, Brisbane, Australia. 9-18.
Ryle, G. (1949). The Concept of Mind. Penguin. Harmondsworth UK. 28.
Scouler, K. (1998) The influence of assessment method on student's learning approaches: Multiple choice question examination versus assignment essay. Higher Education. Kluwer Academic Publications. Netherlands. 453-472.
Veal, D., Maj, S. P, Fetherston, T. & Kohli, G. (1999). Competency Based Assessment Techniques for use in a Computer Installation and Maintenance Unit. Paper presented at the 3rd Baltic Region Seminar on Engineering Education, Goteborg, Sweden.
Weightman, J. (1994). Competencies in Action. Institute of Personnel Development, London. 125 -126.
Whitelock, D., Scanlon, E. and Taylor, J. (1999). Investigating adult learners solving physics problems with the computer, sitting side by side and working at a distance with a networked computer and an audio link only.
http://iet.open.ac.uk/calrg/plant/learnersolving.html [Accessed 28 Dec 1999]
Physics based MCQs developed for the CIM Unit
Fluid flow between a pressure gradient
1. A hard disk drive internally
Potential hazards presented by stored charge
- is at a pressure greater than atmospheric then should a slow leak develop any resulting air flow would be outward thus reducing the chance of outside contamination entering the drive..
- has an inert gas at low pressure to reduce chemical reactions with the disk's magnetic surfaces.
- is a vacuum to prevent airborne contamination.
- is at the atmospheric pressure of the surrounding air but has a special cleaning hatch to enable first line maintenance personal to dust the disk surfaces to help reduce the build up of potential contaminants.
- contains air at the pressure of the surrounding outside air and is factory sealed in
a special clean area to reduce airborne contamination.
2. A desktop PC monitor disconnected from its mains power source
Possible safety implications arising from the incorrect wiring of a mains plug.
- does not present any danger from electric shock due to stored electric charge.
- presents a potential hazard due to stored charge who can still cause a serious electric shock.
- presents no potential hazard due to stored charge because any charge will leak away after power is disconnected and before the cover is removed.
- the stored electric change is at too low an electrical potential to cause a serious electric shock
- the amount of charge stored would be low and hence current flow would be too low to cause a serious electrical shock.
3. An incorrectly wired mains plug on the power lead of a PC could result in
The possible effects of an electric shock on the body.
- the metal case of the PC system box being at live or active potential
- no danger as modern electrical and electronic appliances activating special cut-outs to prevent any dangerous situations occurring from such a situation.
- no danger to users of the PC as the case it is not possible for the metal case of the computer to be electrically connected to any of the metal prongs on the mains power plug.
- no danger because even if the system box were at active or live potential then a user could not receive an electric shock because any electrical current would find an easier path to flow through the desk or table to ground rather than through the user.
- a situation where the metal case is at active or live mains potential then the mains fuse or trip switch would always cause power to be cut off to the machine.
4. People can possibly die due to electric shock due to
- heart failure.
- severe burns.
- the effect of being thrown by the shock.
- neither of the above.
- any of A, B or C or in combination
The following sets of competencies were defined via functional analysis and the listing of the tasks involved in the unit workshops in the CIM unit. Each set should be tested more than once on the unit to give students a fair change to demonstrate attainment of that competency.
CBAs have been developed and tested. The following CBA was developed to test aspects of student understanding and awareness of electrical circuit continuity and voltage measurement for a PC power supply unit (PSU) and its associated low voltage cabling. Note it has been found by the authors of this paper that it is best to test only two sets of competencies during a workshop to avoid tutor overload and resulting errors. Tests for the competencies A and B are as follows.
- Testing, checking and correction
- Safe work practices and protection of equipment
- Manipulative awareness and skills
- Interpretation of instructions. Knowledge of systems.
|A. Testing, checking and correction|
|[ ]||1 Mark||Tests +5V line.|
|[ ]||1 Mark||Tests 5V line on power leads|
|[ ]||1 Mark||Suggests fault|
|[ ]||1 Mark||Suggested possible correction|
|[ ]||A subtotal of marks|
|B. Safe work practices and protection of equipment|
|[ ]||1 Mark||Disconnects from mains when appropriate.|
|[ ]||1 Mark||Takes power lead out of back of system box.|
|[ ]||1 Mark||Uses anti-static strap at appropriate times.|
|[ ]||1 Mark||Polarity of all cables correct.|
|[ ]||1 Mark||Sets digital voltmeter to measure voltage.|
|[ ]||1 Mark||Sets digital voltmeter to the correct range.|
|[ ]||1 Mark||Turns off digital voltmeter|
|[ ]||B subtotal of marks|
|Total of marks for A and B = [ ]|
This marking scheme uses binary marks of 1 or 0 in an attempt to keep the marking simple and thus also help to aid consistency. CBAs on the CIM and NIM unit were specifically designed to enable one tutor to perform the process as part of a general workshop.
|Please cite as: Veal, D., Maj, S. P. and Swan, G. I. (2000). Physics for hands on units in Computing Science. In A. Herrmann and M.M. Kulski (Eds), Flexible Futures in Tertiary Teaching. Proceedings of the 9th Annual Teaching Learning Forum, 2-4 February 2000. Perth: Curtin University of Technology.
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