2.11 Design Principles of the CBA ItemBuilder

2.11.1 Content Experts as Item Developers

Creating good assessment items depends primarily on creating task contexts in which understanding can be applied and, where appropriate, knowledge can be demonstrated. As general as the concepts of computer-based testing and psychometric assessments are, as specific are the application areas and domains in which diagnostic questions are to be answered. The CBA ItemBuilder is therefore designed in such a way that content experts can use the software to create, test, and ultimately use items for computer-based assessments. The technical platform should support a wide range of possibilities of more innovative, technology-enhanced item formats, which is why the CBA ItemBuilder goes beyond the simple, although standardized item formats of IMS QTI and allows the design of multi-page interactive items.

2.11.2 Model-based Representation

The CBA ItemBuilder uses a component model to enable the graphical design of assessment contents. Starting from individual pages, the position of elements and their properties are defined with the help of a graphical editor. In the current version of the CBA ItemBuilder, this graphical editor is a program that can be installed on the computer (see section 1.1). With this program the abstract component model becomes the basis for the creation of assessment content. The visual part of the component model comprises pages (of different page type, see section 3.4), and the graphical Page Editor allows to add components from the so-called Palette to the pages. The components have various properties, such as the position (in pixels X and Y), the size (in pixel Width and Height) and many more (depending on the type of a particular component). The component model is stored within the item definition (in so-called Project Files) and used to generate source code (or a configuration file that can be used with a particular piece of software, called TaskPlayer API) that is used to use CBA ItemBuilder content in assessments.

2.11.3 Separation of Layout and Logic

The model-based representation of the assessment contents (using the component model as describe above), as implemented in the CBA ItemBuilder, is also the basis for a possible long-term archiving strategy of computer-based tests (see section 8.7.3). The basic idea here is that the runetime code can be updated from the model if a newer version of the CBA ItemBuilder can open project files of previous versions (see 3.2.1).

2.11.4 Containers and Nesting

Containers define which components can be added as child elements (i.e., only components of a particular type can be nested within containers of a particular type). Moreover, using the concept of containers, the order in which components are displayed (the so-called Z-Order, the sequence in which components are rendered on top of each other if they overlap) is defined for pages created with the CBA ItemBuilder. Containers are always rendered below their child elements. If a component is a container, the Z-Order of its nested components is defined by the order of the components within the container (see section 6.8.5 for details on overlapping components). Hence, the order in which components are added (i.e., the order within the Component Edit view) defines the order in which components are displayed on top of each other during runtime (i.e., in the Preview and when assessment components created with the CBA ItemBuilder are used in assessments).