a course in basic digital electronics for a distance
TRANSCRIPT
A Course in Basic Digital Electronics for a Distance Educational Programme
Bengt Oelmann and Mattias O’Nils
Department of Information Technology and Media,Mid Sweden University, SE-851 70 Sundsvall, SWEDEN.
E-mail: [email protected]
Abstract - In this paper the design and implementation ofa course in basic digital electronics for distance learning isdescribed. The course is intended to be flexible in order forthe students to follow course without restrictions in time andlocation. The paper discusses flexible lectures, laborations,forms for examinations, and communication between andamong students and course instructor. The course is a part ofthe Swedish nation-wide distance educational program inelectrical engineering.
I. INTRODUCTIONIn order to broaden the possibilities for new groups of
students to enter study programs at the universities,courses based on distance learning is an important way toachieve this. For adult students who work, have families,and live in rural areas, distance learning is often the onlyway for getting an eduction. Flexibility is the key issuewhen designing a course. The course must be design insuch way that it fits in to schedules set by work and familyand overcome geographical distances. Also on-campusstudents may find these courses valuable to resolve coursescheduling conflicts with other courses.
In comparison to on-campus courses normally basedon lectures, distance learning courses have to a largeextent rely on technical aids. Internet based tools are obvi-ously the most important technology when broadbandsubscription becomes available to a large part of popula-tion to a reasonable cost. The open question is how to usethese tools for bridging the distances in location and time.There are many ways to organize a course with respect toorganizing lectures, examination, interaction with stu-dents and among students. For courses in the engineeringdisciplines the laborations are important part that requireaccess to experimental equipment and appear to be amajor problem.
The course in basic digital electronics described in thispaper is a part of a nation-wide initiative called EngineerOnline. The objective is the have a full educational pro-
gram in electrical engineering leading to the degree Bach-elor in Science in Electrical Engineering (BScEE). Inorder to manage to develop a full program in short timeseveral Swedish universities are cooperating in this work.Each university is responsible for developing and carryout two or three courses.
For the course discussed in this paper we have theambition to make it completely flexible in time and loca-tion. No activities are scheduled except for deadlines forhanding in assignments and exams. The students can fol-low the course without having to travel to an universitycampus or a study centre. The course contents is wellestablished by running it for many years as a campuscourse. The challenge is to transform it for distance learn-ing with the goals setup for flexibility and the constrainton how many working hours could be spent on transform-ing it.
Fig. 1: Co-operating universities
Luleå University of Technology
Umeå University
Mid Sweden University
University of Gävle
Örebro University
University of Kalmar
Blekinge Inst. of Technology
Växjö University
Luleå University of Technology
Umeå University
Mid Sweden University
University of Gävle
Örebro University
University of Kalmar
Blekinge Inst. of Technology
Växjö University
From Figure 2, it can be seen that there is a large differ-ence in the student’s age distribution between thoseenrolled in the campus course and those in the distancecourse. Slightly more than 80% of the campus studentsare between 20 and 25 years old. For the students in thedistance course they are more evenly distributed in agesfrom 20 up to 40 years old. These numbers, based on sta-tistics of our students, confirms the assumption that dis-tance learning courses are attractive for adult students.
This paper discusses how we organized flexible lec-tures and laborations with additional support for the stu-dents to actively follow the course. The outline for the restof the paper is as follows. In Section 2 the overall organi-zation of the course is presented. Section 3 discusses theweb-based lectures and section 4 presents the role of thelaborations and exercises. In section 5 we discuss theadvantages and short-commings of our approach based oncourse evaluation questionnaires from the students.
II. ORGANIZATION OF THE COURSEThe organization of the course inherits the basic struc-
ture of the campus course with lectures, exercises, andlaborations. The differences lies in the way the how theyare carried out, the way communication with the studentsare made, and how examination is made. The key issue toaddress is to maintain clear and accurate communicationwith the students. In a campus course with direct face-to-face communication misunderstandings and ambiguousinformation are easily resolve while in distance learningthis may lead to large damage and miscontent among thestudents.
The course is composed of eight elements which are allwell-defined and specified by the following:• Contents• Learning goals; formulated as “After completion ofthis element you should be able to ...” with objectives for-mulated according to Bloom’s taxanomy [1].• References to recommended textbook reading andexecersises• Obligatory laborations for this element• Examination for this element
In order to stimulate the students to be active duringthe whole course period, we use continuous examinationthat has been shown to give good results [5]. This meansthat the examination of the course is evenly spread overthe whole course period. The course examination is basedon three written exams, denoted T1-T3, and three labora-tions, denoted L1-L3. The written exams are the basis forthe student’s grade and the laborations are obligatory butnot graded. We view the laborations as an importantmethod for learning and understanding the topic ratherthan a way for examination.
The course is web-based supporting all communicationbetween the instructor and the students.
The purpose of the web-pages is to house all informa-tion and documents needed to follow the course.
In communication with the instructor, the students areencouraged to use the discussion forum before using e-mail. Most questions are of general nature and are there-fore of interest to the whole student group. In this waymore active discussions among the students are promotedand the load on the instructor answering questions indi-vidually is reduced.
The course period started week 45 and ended week 3.In Figure 5 the student’s activity, measured in number of
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Fig. 2: Student’s age distribution
Fig. 3: Elements of the course
Boolean Algebra
Combinational Logic
Minimization Methods
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Memories, ADC, DAC
Electrical Interfaces
Introduction to HDL
Fig. 4: Student - Instructor communication
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- course formalities- course plan- study guidance- lectures- excersices- FAQ
Discussion Forum
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e-mails and posts in the forum, in communication usingthe discussion forum and e-mail is shown. The activity isquite evenly distributed over the whole period with theexception of week 52 during the Christmas holidays. Thedeadlines for handing in laboration reports and exams,indicated in Figure 5, are evenly distributed.
III. LECTURESThe purpose of the lectures is the introduce the stu-
dents to the various topics and point out the key issues toenable self studies. Most of the techniques and methods indigital electronics is very suitable to be illustrated graphi-cally and therefore suitable as animated powerpoint pres-entations. Some examples are Karnaugh-maps, schematicdiagrams, timing diagrams, and the operation of finite-state machines in state transition diagrams.
Teaching by lectures is the most common way in cam-pus courses. For distance learning courses it is questiona-ble whether it is the appropriate form or not. Videoconference systems for lecturing is one commonly usedapproach that makes it possible for two-way communica-tion during the lectures. This is a synchronous form thatwe do not find suitable since it is not flexible in time. It doalso put high requirements on the student’s Internet con-nections. Another form is video recorded lectures that canbe distributed asynchronously via the Internet or mail.Producing live recording of lectures in a campus coursewith good quality is not straight-forward. The problem isthat such recording contains scenes and sounds not rele-vant and moves the focus from the material to be pre-sented. It is also difficult to incrementally update parts ofthe material.
We choose to base the lectures entirely on animatedOH-presentations in Powerpoint. A speaker voice isadded, which is the lecturers comments to the slides. Theadvantages are that the information can be focused, thematerial can easily be updated by replacing or addingslides. We have one lecture for each course element andeach lecture is approximately 60 minutes each which isapproximately the same length as for the campus course.The lectures are viewed in any web-browser using theFlash format [2], see Figure 6, that we found most effi-cient with respect to compression. The recorded materialrequires 136 kbytes per minute which gives a total of 62Mbytes for the all lectures (7.5 hours). The material wasproduced by recording the powerpoint slideshow using
Camtasia [3] that captures the screen resulting in a videosequence. At the same as the lecturers’s voice is recorded.As a complement, the lectures were also distributed asordinary handouts in pdf-format.
IV. LABORATIONS AND EXCERSISESIn the engineering disciplines, laboration is an impor-
tant part for learning the topic through hands-on experi-ences. This is however very difficult to accomplish in adistance course. One solution is to arrange one or twomeetings on-campus when all laborations are carried out.This is obviously preventing many of the students to par-ticipate. Another way is to send out inexpensive lab-kitsso that the labs can be done at home. The disadvantageshere are that only very low-cost equipment can be distrib-uted that is not adequate and therefore does not reflect theequipment normally available to engineers. We choose touse simulations as a substitute to laborations with physicaldevices and instruments. In a course in basic digital elec-tronics we believe that for learning most of to topics this issufficient. By considering that a digital designer usesexclusively CAD (Computer Aided Design) throughoutthe design process, makes this approach adequate.
Many free-of-charge CAD-tools with schematic editorand simulator are today available. Some textbooks comewith student versions of professional tools that are insome way restricted. These are typically more than suffi-cient and gives the student the experience in using a pro-fessional tool. They are, however, quite complex andcontain many functions not needed for the course whichmakes the threshold to learn how to use them unnecessar-ily high. We choose to use a tool, called Dsch2 [4], devel-oped for educational purposes only which makes it easierto learn and use. In Figure 7 a screen capture of the tool isshown.
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Fig. 5: Student activity time-line
Fig. 6: Screen capture of animated lectures
The laborations have a great potential to be the part inthe course where interactions between the instructor andstudents as well as interactions among the students thatcan support learning very well. Discussions in the forumabout how to solve the problems can be freely discussedwith many participants since the laborations are manda-tory but not a part of the examination.
In an on-campus course often teacher-assistanced exer-cises are used to support students to learn solving prob-lems. In the distance course we have simply publishedsolutions to a number of problems from which the stu-dents can see how to proceed.
V. DISCUSSIONSThe development of Internet based learning enables
many new possibilites for distance eduction. Softwaretools, such as WebCT, supporting the setup of web-basedcourses and inexpensive ways to produce video-based lex-tures are also available. Using some of these techniquesmay however require lots of resouces in order to developthe material. When transforming a campus course to a dis-tance course it is important to identify the key issues thatenable students to follow the course independently oflocation and time. As a developer of a distance course, thetime spent on course development is often very limited. Itis therefore important to focus on the key issues that sup-port the students to study the topic more independetly thanon-campus students. In the course discussed in this paperwe have kept the basic structure from the campus coursewith lectures, execercises, and laborations. The lectureswe consider to be one-way communicaton from theinstructor to the students. Here the key issue is to presentthe central topics in a clear and precise way. The excer-cises with solutions shall through examples illustrate themethods of solving problems.
In Figure 8 part of the results from the course evalua-tion is shown, where the students have graded differentaspects of the course with 5 as the most positive and 1 asthe most negative grade respectively. In general the stu-dents had a more positive view on the course than studentsnormally have on an on-campus course. In average thestudents found the labs to provide the best support fortheir studies. The excersices were found the be very usefulbut several commented that it was difficult to learn fromwritten solutions alone. Animated solutions with speakervoice were therefore requested by the students. Theinstructor-student communication were found to be goodand quick responds by the instructor was important.
The major part of the development time was needed forpreparing the animated powerpoint presentations withspeaker voice. At the end of the course (week 3) approxi-mately 50% of the students had completed the coursesucessfully. Many of those not completed the course stillhad to hand in laboration reports.
We have shown how an established on-campus coursein digital electronics can be converted into a flexible dist-nace course using streaming media and simulation tools.
VI. ACKNOWLEDGEMENTSThe authors acknowledge the support of this work to
the program coordinator Anders Nelsson at BlekingeInstitute of Technology and Lars Logenius, Head ofunder-graduate studies at ITM, Mid Sweden University.
VII. REFERENCES[1] Bloom, B.S. (ed) Taxonomy of Educational Objectives,Handbook 1: Cognitive Domain New York: Mckay, 1956.[2] http://www.macromedia.com[3] http://www.techsmith.com[4] http://intrage.insa-tlse.fr/~etienne/Microwind[5] Hake, R.R.. 1992. "Socratic pedagogy in the introductoryphysics lab," Phys. Teach. 30: 546-552.
Fig. 7: Screen capture of Dsch2 schematic
Fig. 8: Student’s course evaluation
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