Teaching Planning - Guide to Teaching Computer Science: An Activity-Based Approach - page 204

of modularity, educators start from simple tasks, and gradually progress to compli-
cated ones. However, for some meaningful concepts this approach is not applied
naturally. In such cases, it is recommended to carefully plan the teaching process,
exposing the learners to the essence of the concept gradually along the curriculum.
This kind of interpretation requires a broad view of the whole curriculum planning,
integration of exercises that enable to overwhelm the concept along the curricu-
lum, and conduct discussions of the concept. This methodology enables students
to gradually build their understanding in the spirit of the constructivist learning
approach.
A good example for such an approach is with respect to the concept of algorithm
efficiency, which is usually referred to as “hard to accomplish”. This is exactly the
reason why efficiency should be presented gradually, instead of presenting it for
the first time much later by sort algorithms, as is done in most cases. In the case of
algorithms efficiency, the spiral gradient teaching could be done, for example, by
the following exercises:

1. When teaching conditions, one of the very first exercises is “Find the biggest
number out of three numbers.” Even in this simple case, we can discuss the num-
ber of conditions used in different solutions and show a solution that uses only
two simple conditions.
2. When teaching loops, one of the common exercises is: “Print all the divisors of
a number n. ” Here we have the opportunity to look at a loop that repeats till n —
looking at all the numbers smaller than n ; a loop that goes till n /2—looking at the
optional dividers; and a look at loop that goes till

n —till the largest possible

divider.
3. When teaching arrays, we usually use the next exercise: “For n input numbers
print the most frequent number.” Here, we must use double loops, while the inner
loop can be twice smaller on average; when proceeding to counter arrays we can
change the exercise and talk about a case when the range of the values is between
1-100 and use only one loop.

Such exercises, as well as the discussion that follow the presentation of their solu-
tions, should be integrated along the curriculum.
More exploration on the teaching of efficiency to novices can be found at Ginat
( 1996 ).

11.3 Illustration: Teaching One-Dimensional Array

We now demonstrate the teaching planning of one study unit by focusing on the topic
of one-dimensional arrays (Sect. 11.3.1), and the teaching planning of one specific
lesson—the first lesson about arrays (Sect. 11.3.2). Needless to say, other possible
planning processes exist and the presented planning is just one option among many.