Teaching Methods in Computer Science Education - Guide to Teaching Computer Science: An Activity-Based Approach - page 118

2. A group presents its additional new instance for a specific group and
the class should guess which of the presented instances in the work-
sheet belong to this set.
3. A group presents its title for one of the sets and the whole class should
guess which instances belong to that set.
During the discussion, the instructor should encourage a dynamic dis-
course and introduce generalizations and formal terminology with respect
to control structures . Learners in general and the prospective computer
science teachers in the MTCS course in particular, are often exposed in this
discussion to new concepts and to different ideas and perspectives. This
exposure, in turn, encourages them to reconsider their previous perspec-
tive at the topic (control structures, in this case) and to modify it, if needed.
The discussion can end with a summary of the main concepts related to
control structures that have been introduced in this activity.
• Stage C: Construction of a classification activity, homework

After the classification activity is facilitated with respect to control struc-
tures, it is recommended to ask the students to construct a similar activity
with respect to another computer science concept (as a course activity or
as homework). As a preparation for this activity, it is important to discuss
with the students the essence of the concepts for which such an activity fits
and to define criteria for the selected items. We mention here that recur-
sion (see Chap. 12 for a similar activity), abstraction, and data structures
are appropriate candidates for this purpose, and that the items selected
to be included in the worksheet should clearly (and not in a hidden and
sophisticated manner) reflect the illustrated concept. While preparing such
an activity, it should be remembered that such classification worksheets
are constructed for novice learners who are not familiar yet with the con-
cept on which the worksheet concentrates, and therefore, the image or text
should direct them clearly and safely in the identification process of the
properties of the said concept.

We end this section by noting that although the classification activity is usually
designed as an opening trigger in the learning process of a new concept, it is also
possible to use it as a summary activity. In this case, all the stages and instructions
will be facilitated in a similar way; learners' behavior, however, will be naturally
different since they will be familiar with the main concepts/aspects of the said topic.

7.2.6 Metaphors

Metaphors are used in order to understand and experience one specific thing by
using an analogy to another thing, usually a familiar concept (Lakoff and John-
son 1980 ). Many metaphors are used in computer science on a regular basis; just