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[ Index | Introduction | Expositive | Demonstrative | Interactive | Practical | Conclusion | References ]
The first methodology analyzed
is called expositive. Theory, definitions, hints and many other features
that translate traditional textbooks in "electronic books" are
typical examples of expositive materials. In our course a hypertextual
environment is the default choice, with its capability of structuring text,
images and links [10], [11].
It must be stressed that
delivering expositive material with a multimedia computer instead of the
classical communication media (print or speech), does not modify the position
of the learners and does not remove the risk that they behave as passive observers.
In our past experience
of courseware developers we have noticed that hypertext did not prove itself
very successful with students [12]. Even
if the use of the hypertext as the main vehicle to convoy information to
the learner showed some advantages over a textbook [13]
under the point of view of material organization, indexing and search facilities,
our students still preferred to learn the theory on their class notes.
Consequently, in successive revisions of the courseware, the hypertext
has been enhanced by reducing the number of static words on the screen,
replacing them with figures, schematics and pop-up windows. In synthesis,
hypertext function
is to provide the framework of the lesson and to link together animation
and local tools that provide a more operational explanation, acting therefore
as the connective tissue between the learning tools [14].
Fig. 2
represents an example of our implementation of the guidelines described
above. A textual explanation is present on the left end side and can be scrolled
independently of the picture on the right end side. Navigation buttons,
on the bottom, are standard components of the GUI. The combination of
text and figure explains the concept of two-dimensional memory addressing.
The page shown in Fig. 3 follows immediately in the
pedagogical sequence the one described in Fig. 2. The
same concept of two-dimensional memory addressing is explained with the
use of a learning tool that encourages the learner to verify actively the
concept. The binary values of the memory address lines can be set by the
student with a mouse click. The number and position of the decoders output
lines change accordingly. The HELP button provides instruction on how to
operate the tool.
The screen-shots
presented here as static figures are part of the courseware. The reader
can take the role of the learner by running a working example
[15].
The hypertextual structure
of our courseware has been enriched with the animation of most of the concepts,
networks and algorithms. Animation targets specifically the understanding
phase of learning, trying to form an intuitive idea of a concept. Some
descriptions of processes that can be difficult to explain by text only
become, in fact, very simple and intuitive if the text-based description
is substituted, or integrated, with direct animation. This feature is especially
useful when exposing fundamental concepts. A field where animation is particularly
useful is the introduction to Finite State Machine (FSM). In our course,
digital systems are represented with the model of the FSM and the Algorithmic
State Machine (ASM) [16] method is applied
to both Moore and Mealy machines. Therefore, an introductory course like
ours takes the most advantage of animation, that provides a visual representation
helping the student to conceptualize some unfamiliar aspects of digital
electronics.
In our classification of
learning tools, we make a distinction between animation used in an expositive
context (to introduce theoretical concepts) and in a demonstrative context
(to show how an existing device or network operate). In this paragraph
we provide two examples of expositive animation. Fig. 4
shows the difference between a state and a conditioned output in a FSM
by displaying the parallel evolution of ASM chart and its timing diagram.
Of course, a better understanding of this tool can be gained by running
the working example.
The timing of all the animated
features present in the courseware is controlled by the learner, because
our experience has shown that a free running animation is often refused
by the student that does not like to be paced externally. Therefore each
animation is divided into steps that are controlled by the learner with
the possibility of stopping or repeating the process or part of it.
This last feature is exemplified
better in Fig. 5, representing a typical microprocessor
output operation. The animation explains address decoding and data
transfer to the output register. It is useful to provide a few words of
explanation for the buttons
present on the screen. The blue ones belong to the graphical interface
adopted through the courseware and their function are standard (navigation
and help). The "camera" button on the bottom right starts the
animation: each step not only modifies the image, but also generates an
explanation window, that contains the green buttons allowing navigation
inside the animation itself. The timing diagram button on the left of the
"camera" shows a time domain representation of the process (working
example).
Fig. 2. An example of a typical hypertext page.
Fig. 3. A hypertext page including a simple learning tool.
Fig. 4. Animation explaining the difference between a state output and
a conditioned output
in a FSM described by an ASM chart.
Fig. 5. Animation of the process of a microprocessor transferring a byte
of data to an output port.
