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The pair fail to accommodate reference semantics within their understanding of assignment and variables,
and resist the alternative view of program behavior suggested by UUhistle. They decide that references
are merely a misleading “feature” of UUhistle. In their later work during this session they show no sign
of reconsidering this view. 8
This was the only case we observed in which the students explicitly challenged the fidelity of the
visualization.
Ignoring aspects of the VPS environment
Let us now consider some things that students did not do and or pay attention to.
Again, the following analysis is based on dialogue and students’ use of the mouse. We did not, for
instance, use eye-tracking equipment, nor did we have video of students’ bodily gestures. Nevertheless,
we can comment on a few elements within the VPS system, which, our data suggests, some students
entirely ignored.
Many of the students we observed had already ignored some available sources of information before
they started on the VPS task proper.
The first VPS assignment was prefaced with short instructions, which were visible onscreen before the
simulation task started. The large majority of the students clearly did not read these at all or only granted
them the briefest of browses.
Numerous student pairs also ignored the program animation provided as an introductory example of
the topics covered (see the next chapter and in Appendix C). The example of lists and references appeared
in UUhistle’s assignment selection menu right before the two VPS assignments. However, nearly half of
the 41 pairs did not start by watching the example, instead jumping directly to the VPS task (usually
without reading the instructions for that task, either). From our data it is clear that failing to read the
instructions was invariably associated with significant puzzlement and trial-and-error tactics regarding list
operations right at the start of the first VPS task. The students who had skipped the example and the
instructions had little idea of what steps are involved in carrying out a list operation in UUhistle and in
what order (e.g., to produce a new list, you had to first create a list in the heap, to form a reference to it
in the evaluation area, and finally to initialize it). Only after flailing about, usually clearly frustrated, did
the pairs eventually figure out how to move forward. We must be careful as we consider the causalities
of the situation. It is possible that another factor (e.g., a certain attitude or approach to learning) led
some of the students both to skip the example and to struggle with the list operations. Nevertheless, it
seems to us a very reasonable conjecture that the failures to look at the example and the instructions
contributed significantly towards the students’ troubles.
After they completed the second VPS assignment, students often checked UUhistle’s assignment menu
again to see if there was anything more they were required to do. At this point, many of the pairs who
had not initially watched the example animation did go back to watch the example. Viewing the example
afterwards almost invariably led to dialogue such as this:
Kate 33 : This is one of those where you have to just, like, click your way through it.
John 33 : Ow! If we had only watched this in the beginning, this one!
Kate 33 : Uh-huh. Laughs without humor.
During the VPS exercise itself, students’ attention was primarily on the program code and the graphical
elements they manipulated. The majority of pairs did not explicitly refer to program output at all. Even
fewer pairs appeared to reflect thoughtfully on what was printed out. None of the students ever looked
at UUhistle’s menus at any point for any purpose except to change assignments.
The vast majority of the pairs never used the feedback button to request textual feedback on their
solution. The example on page 306 is one of only a handful of individual episodes where someone did ask
for feedback.
8 From a pedagogical point of view, this is not exactly a happy outcome. However, we may still speculate (and hope) that
this experience may have been a memorable one for the pair, and they perhaps came to recall it at some later stage of the
programming course, such as when references created a bug in their own program.
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