Abstract:

Amplifiers are basic components of electronic circuits and, as such, lie at the core of most electronic engineering courses. In an attempt to help students comprehend the basic theoretical and practical facts of amplifiers and dissolve relevant misconceptions, concept maps are used to present the various types of electronic amplifiers in a 2-hour lecture which is part of the 3rd-semester “Electronics II” course offered at the Dept. of Electrical & Electronic Engineering Educators, School of Pedagogical & Technological Education (ASPETE), Athens, Greece.

Concept maps are used to present the following types of amplifiers:
- Bipolar-junction transistor (BJT) amplifiers.
- Field-effect transistor (FET) amplifiers.
- Operational amplifiers.

From the methodology point of view, after a short briefing on what they are expected to do together with an overview of the various amplifier types, the students are asked to classify amplifiers with the use of a concept maps following the procedure explained below:
The students are first asked to develop concept maps for the amplifier types they are more familiar with, that is BJT and FET amplifiers. For the students to build a better overview and enhance their conceptual understanding, the concept maps should include a short reference to the basic facts and applications of the involved amplifier types. Then the students are asked to find possible interrelations between the relevant concept maps and, at the same time, add the operational amplifiers without and with feedback.

At a final step, the students are asked to associate the various types of BJT, FET and operational amplifiers with the notion and the various types of controlled sources that is, voltage-controlled voltage source (VCVS), voltage-controlled current source (VCIS), current-controlled voltage source (ICVS), current-controlled current source (ICIS) which are in turn characterized as such on the basis of their input and output impedance. Following a brief review focusing on the BJT CE amplifier, the students are asked to form an alternative concept map in which the various amplifier types are associated with a specific type of controlled source (VCVS, VCIS, ICVS or ICIS).

At present, the use of concept maps regards the Content Knowledge (CK) and Pedagogical Knowledge (PK) parts of the TPACK framework. The aim is the students to develop Pedagogical Content Knowledge (PCK) in view of their possible future employment as secondary school teachers. Regarding Bloom’s revised taxonomy, the presentation mainly covers layers 2 and 3 (understand and apply) and maybe layer 4 (analyze). A future presentation could anticipate the formation and elaboration of concept maps with the use of computer tools that would also add the Technological Knowledge part (TK) and also enhance layer 4. The whole process anticipates students’ active participation.

At the end of the lecture, a short questionnaire was distributed to students (three questions on the usefulness of concept maps) that should be answered by means of a 5-grade Linkert scale (“1” strongly disagree, “2” disagree, “3” neither disagree nor agree, “4” agree, “5” strongly agree). In all three questions, the average in the answers was equal or higher than 4.0 which shows that students generally agree on the value of concept maps and their ability to improve understanding, in this case on electronic amplifiers.

Keywords:

Engineering Education, Electrical Engineering Education, Electronics; Amplifiers, Concept Maps.