Maria Knobelsdorf, University of Dortmund, Germany - Didaktik der ...

y choice of handset, choice of network provider, and of course
by the individual pattern (also named habits, see [31]) in using the
mobile phone.
5.2 Algorithms in text-processing
Typically text processing is associated with ICT, and with teaching
usage. Sometimes, e.g. the object oriented analysis of text
processing is part of teaching Computer science, but predominantly
only function is analyzed (see e.g. [15]). But text processing
can also be used to demonstrate structure so that such knowledge
helps understanding the sometimes ‘irrational’ or ‘unpredictable’
behavior of text layout. A typical question of users might be:
“Why aren’t my pictures where I wanted them to be?”
In order to answer such a question, a course can start with the
historical example of Donald Knuth’s endeavor to capture the art
of computer programming, and his task to develop TeX in order to
be able to present it in a suitable layout.
One issue involved in developing such a text processing system is
line breaking. Paragraphs can be automatically aligned, too. We
are considering justification (as in this article) as the desired style
for paragraph alignment.
In its simplest form, full justification is rendered by filling a line
word by word until a word hasn't enough space, and then the
spaces between words are widened until the line is in full justification
(first-fit algorithm). A more advanced algorithm allows
white space between words not only to grow, but also to shrink
(best-fit algorithm).
Here different line breaks are possible, and thus different possibilities
have to be taken into account and evaluated in order to decide
whether shrinking or growing spaces leads to a better full justification.
The most advanced algorithm takes into account not only
the current line, but the whole paragraph. E.g. by omitting a local
maximum the global maximum for the paragraph can be optimized.
This is the total-fit algorithm developed together with TeX
by Donald Knuth and Michael Plass [18].
Thinking about these possibilities alone can help students to be
able to perceive the structure of text processing. To do this, an
experiment can be conducted in which students try to figure out
whether the local text processor (like e.g. Open Office or Microsoft
Word) uses total-fit.
If so, within a paragraph line breaks can change, if the last line of
the paragraph is altered. This should be observable in WYSIWYG
(“what you see is what you get”) text processors. Usually – at least
in our experiments with students – they don’t see such changes, so
the conclusion is that modern WYSIWIG processors do not use
the best algorithm available. However, maybe the data used in the
experiment didn’t reveal any changes, but with other text input it
would. On the other hands students might argue that changing line
breaks in already finished lines while typing would be confusing.
A web search can be added to check if producers of word processors
provide any information about the algorithms used.
However, the main learning goal of the experiment is not to figure
out which algorithm is used, but to understand that algorithms are
used, and that there are differences, and a lot of things happening
while the function experience suggests that simply characters
from the keyboard are ‘typed onto the screen’.
Does this help to better use text processing and e.g. prevent pictures
from being placed by random within a document? Short
answer: No (A longer answer will follow below). Is CS Education
(for Outsiders) therefore useless? Again: No. Let’s compare this
to science: What is the ‘use’ of knowledge about the solar sys-
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tems, and planets circling? A sunset is still a sunset – yet many
people would agree that knowledge about the world is worthwhile
in its own. Similarly, bridging function to structure enables learners
to perceive structure, to get a better perception and understanding
of the digital world.
In summary, there are three intended effects of examples like this:
First, some learners should become intrigued to explore this world
further and e.g. learn what an algorithm is in detail.
Second, this understanding should be transferred to other aspects
of word processing, namely the example mentioned at the beginning:
Why can it be that pictures are seemingly moved randomly
around the text? A closer look here reveals that (usually) the user
has the option to change which algorithm is used to place the
picture on the page. So in a specific manner, this example might
also reduce difficulties in using.
Third, self-efficacy should be increased. As this experiment introduces
algorithms, but in the context of everyday use of ICT, it
builds a bridge to structure: Outsiders should experience and
notice that they have the ability to understand and gather such
structure-knowledge.
5.3 Search engine results
In this example, the notion of ‘personalized web search’ is experimentally
analyzed, using a method based on [11]. The question is
how the result-lists of Google are compiled, especially whether
everybody gets the same results.
Freuz et al. [11] designed an experiment to analyze this. They
opened three Google accounts (Kant, Nietzsche, and Foucault),
and performed individually different searches, and so allowed
Google to collect a search history of the accounts.
Afterwards they compared results of the three accounts to some
selected common searches. It became clear that within the first
page of presented results, the three accounts got different answers
to the same search term.
The interesting aspect here is the methodology used: Focusing on
the user experience (function), a scientific experiment is devised:
Using a hypothesis, a methodological setup, and the gathering of
data which has to be analyzed and interpreted. The remarkable
thing about this experiment is, that mainly operating within the
usual user paradigm (within the framework of function), the experiment
reveals novel insights in the function but at the same
time also insights in the internal mechanics (structure).
Students can learn that by engaging in thorough observation it is
possible to infer structural aspects relying on normal usage only.
6. DISCUSSION
In science teaching, experiments are a well-known teaching method.
E.g. science labs offer courses for interested schools, where
learners can experience interesting experiments. Although quite
successful, such activities are sometimes labeled as “hands-on,
minds off”-approaches.
While these activities - that’s the essence of the saying - are very
good in triggering situational interest, as they provide most often a
quite spectacular experience, they are less good in developing and
maintaining individual interest.
In research on interest, situational and individual interest is differentiated.
Situational interest is conceptualized as being due to
external causes, by catch facets like e.g. new approach to teaching
or an interesting puzzle to solve [25]. Thus, the teacher can catch
the attention, and situational interest is triggered. Individual inter-