Problem-Solving Strategies - Guide to Teaching Computer Science: An Activity-Based Approach - page 77

Each pair presents to the course plenum one of the problems it developed.
For each problem, the pair should explain why it is important to start its
solving process with the examination of inputs and outputs.

If possible, the course instructor should choose the problems that the pairs
present in a way that enables discussion on different aspects and topics.

It is recommended to publish all the developed questions in the course web
site for future usages either in the MTCS course (see Activity 32 below, for
example) or in the students' future high school teaching.

5.4 Solution Design

Some of the major difficulties novice learners face, when engaged in problem-solv-
ing processes, are concerned with the early stages of the solution design (Soloway
1986 ; Reed 1999 ; Robins et al. 2003 ). In what follows we present three strategies
that may be employed in this stage of the solution design, i.e., defining the problem
variables, stepwise refinements and algorithmic patterns, together with relevant ac-
tivities that examine these strategies from a pedagogical perspective. Needless to
say that the order by which the strategies are presented here is not necessarily the
order by which they should be taught. Alternatively, the order by which they are
taught and used, as well as the level of depth on which each of them is discussed,
depend on the learning stage and the kind of problem in hand. For example, in
simple cases, it is reasonable to start with choosing the needed variables; in more
complex cases, it is worth starting developing the problem solution by stepwise
refinements.

5.4.1 Defining the Problem Variables

The examination of a given problem's inputs and their corresponding outputs, clari-
fies the problem to the problem solver. The next stage is to define the variables
needed in order to solve the problem. Activities 32-34 examine solution design
from a pedagogical perspective.

Activity 32: Choosing the Problem Variables
This activity aims to deliver the message that a deep consideration of the
variables needed for solving a given problem is a crucial stage in the problem-
solving process since it directs the solution implementation.
• Stage A: Problem analysis, work in pairs

Students are asked to further analyze the problems they developed in
Activity 31 and to set the variables needed to solve them. It is recom-