Types of Questions in Computer Science Education - Guide to Teaching Computer Science: An Activity-Based Approach - page 167

9.2.9 Type9. Efficiency Estimation

Description : Students are asked to estimate the efficiency of a given solution.
Example of a general pattern : Estimate the efficiency of the presented method in
terms of big O . Explain your estimation.
Variations : This type of questions can represent different levels of cognitive
complexity, as is described in what follows. (a) A general pattern that enables to
discuss efficiency in early stages of CS learning: Focus on the loop in the given
method: How many times is the loop executed?; (b) Estimate the efficiency of a spe-
cific method (as in the example of a general pattern); (c) Estimate the efficiency of
a method that invokes another method, when the efficiency of the invoked method
is taken into the consideration; (d) Compare the efficiency of different methods that
solves the same task; (e) Estimate the efficiency of a recursive method; (f) Develop
of a solution to a given problem with a specific efficiency.
Discussion : Instructors should not wait till they teach complicated algorithms
in order to teach the concept of efficiency; alternatively, questions that deal with
efficiency can be integrated from early stages of teaching and learning CS. For
example, questions, such as the one presented in variation (a), hints at the seeds of
the concept of efficiency that, in general, is considered to be abstract and difficult
for understanding.
Note that variation (f) is actually a “development of a solution” (Type1 question)
with a restriction about its efficiency, which requires learners not to be satisfied
when finding an algorithmic idea that solves the given problem; rather, they should
estimate its efficiency and if it does not fit the restriction mentioned in the question,
they should look for another solution or improve the solution they found.

9.2.10 Type10. Question Design

Description : Students are asked to design a question.
Example1 : Design a question that checks learners' understanding of the sort-
merge algorithm.
Learners' answer to this question can be based, for example, on tracing regular
and/or extreme cases of the input to this algorithm.
Example2 : Design a question in such a way that its solution uses a method that
finds the most frequent value in an array. An example for such a question is:
Pupils' grades in a CS test are given. Write a method that prints the most frequent
grade in this class.
Variations : A design question can relate, among other options, also to the design
of (a) additional tasks in a given question that clarify extreme cases; (b) a question
that its solution should use a given method (as Example2 is); (c) a question that
intends to check the understanding of a specific concept or algorithmic idea (as Ex-
ample1 is); (d) a whole test or worksheet that examines a specific CS concept/topic.
Discussion : This type of questions invites learners to adopt a different point of
view. In addition to the experience learners gain by examining a question from the