Maria Knobelsdorf, University of Dortmund, Germany - Didaktik der ...

the knowledge about ICT and CS (see [3]). CSE as a general
education in German school should comply with these standards.
Question 2: Which contents and processes are used to teach “data
modeling and database systems” according to the individual level
of students (means as different existing knowledge)?
The knowledge about handling computing systems and the
experiences students have in their everyday life are mostly
different. In order to understand general informatics contents and
processes and to use this knowledge in everyday life it is
necessary to use exercises according to the individual level of
students. Doing so, it will be also possible to combine the already
existing knowledge about handling computing systems with
knowledge about general informatics contents and processes.
Category systems
The first question focusses on the “educational standards of
informatics SI”. The competencies relating to “data modeling and
database systems” are used as categories to evaluate the exercises
(see table 3, CS1-PS3). It is investigated which informatics
contents and processes enable the achievement of the competencies.
The presented competencies are connected to each other in
several ways. It was possible to assign more than one category for
each exercise.
The individual level of students can be considered in different
ways (e.g. information representation, teaching arrangement, time
to work on exercises, context of exercises, complexity of
exercises). By using the method applied in this study, it is
possible to investigate the cognitive complexity 4 . In order to
evaluate the exercises three categories (see table 3, ABI-ABIII)
are used. Only one category can be assigned for each exercise.
Table 3. Category systems for question 1 and 2
Code Category and Anchor
Learners understand the connection between data and
information and different forms of representations of data.
CS1 “Choose a problem area where large data volumes are
stored and connected to the internet. What information on
objects, persons, or events are stored in the database?”
Learners understand operations on data, and interpret
these with regard to the represented information.
CS2 “Send the following described queries to the given
database mail-order business.
Give an overview of all clients of a specific city.”
Learners are able to trigger suitable operations on data.
“The following SQL statement is given
CS3 SELECT Artikel.ANr, Artikel.Bezeichnung, Lieferant.LNr,
Lieferant.Name FROM Artikel, Lieferant;
Send a query to the database and interpret the results.”
Learners create informatics models based on given facts.
“Decide which columns are necessary to acquire data in
PS1
the table CD. Complete the current schema with the new
columns.”
Learners implement models with suitable applications.
PS2 “Transfer your current data model into a relational model.
Use the necessary rules and specify the developed tables.”
Learners reflect models and their implementation.
“Check your database mail-order business in accordance
PS3
with the given rules. If necessary, optimize your
database.”
4 Cognitive complexity involves the requirement, the level of
difficultly etc. (see [2]).
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Reproduction performance
ABI “Which information can you receive from the tables in the
database CD? Formulate five questions.”
Transfer performance
“In the last exercise you verbally formulated possible
ABII queries to your database. Describe your queries as
selection, projection or as a combination of both. Express
your queries as SQL-statements.”
Constructive performance
ABIII “Does your database mail-order business guarantee
referential integrity? If necessary, update your database.”
Rating
All exercises were evaluated by one teacher and one student
teacher of CSE. For all categories the inter-rater reliability was
higher than 0.65 (Cohen-Kappa). To get an idea of the rating
method an example for rating an exercise is given first:
Exercise: “A part of the data model CD rental is given. Find other
useful classes/entities for this data model. Complete the data
model with appropriate attributes. Define the cardinality of the
relationships.”
Rating of Rater 1 (n1) and 2 (n2): PS1, PS2, CS1, ABII
All equal rated exercises (N=45) were used to receive a common
grading of the content and process competencies. The grading is
presented in the next chapter.
4. RESULTS
The “educational standards of informatics S1” are developed as
minimum standards. Nevertheless, there are informatics contents
and processes above and below these standards. The answers of
question 1 and 2 emphasize contents and processes to achieve the
standards in three requirement areas.
In order to get an overview of the used material some quantitative
data (see table 4) are given first.
Table 4. Quantitative data of the analysis
Rater CS1 CS2 CS3 PS1 PS2 PS3 ABI ABII ABIII
n1 30 30 26 8 6 21 13 32 16
n2 31 29 24 8 6 23 11 31 19
In regard to answering the first part (contents) of question 1 a
summary of the content standards in exercises is shown in table 5.
Combining the answers of question 1 and 2 results in a grading of
the content competencies (see table 5). In sum, it is shown, that:
� the handling with the database systems turns from simple
usage of the graphical user interface to formal statements,
� the databases and queries turn from given databases and
queries to independently developed databases and queries,
� the use of databases turns from simple usage to evaluated and
improved usage.
However, there are only a few exercises concerning process
standard 1 and 2. It is possible to compile a summary of process
standards in exercises. Combining the answers of question 1 and 2
results in a grading of the process competencies (see table 5). In
sum, it is shown, that:
� data modeling turns from modeling some elements of data
worlds to modeling complete models of data worlds,
� the transfer of data models into database systems turns from
the transfer of given tables and relationships to the transfer of
independently created data models,
� the use of data models turns from simple usage to evaluated
and improved usage.