Organisation and navigation 70. Screen sizes vary dramatically in digital environments, from cell phone displays, which are
smaller than a traditional index card, to large, multiple screen displays for simultaneously showing
multiple screen windows of information. At the time of the drafting of this framework, however, the
typical computer screen (such as the 15" or 17" that come with ordinary desktop and laptop
computers) features a display resolution of 1024x768 pixels. Assuming a typical font size, this is
enough to display about a half-page of A4 or US-Letter page; that is, a very short piece of text.
Given the wide variation in the “landscape” available on screens to display text, digital texts come
with a number of tools meant to let the user access and display specific passages. These tools
range from generic tools, such as the scroll bar and tabs (also found in a number of other software
applications like spreadsheets and word processors) and tools to resize or position the text on the
screen, to more specific devices such as menus, tables of contents and embedded hyperlinks to
move between text segments. There is growing evidence that navigation in digital text requires
specific skills (OECD, 2011; Rouet, Vörös, & Pléh, 2012). Therefore, it is important to assess
readers' ability to deal with texts featuring a high density of navigation tools. For reasons of
simplicity, the PISA 2018 framework distinguishes “static” texts, with a simple organisation and low
density of navigation tools (typically, one or several screen pages arranged in a linear way), from
“dynamic” texts, which feature a more complex, non-linear organisation and a higher density of
navigation devices. Note that the term “density” is preferred to “number” to mark the fact that
dynamic texts do not have to be longer than static texts.
71. For purposes of coverage, the 2018 framework also retains two former dimensions of texts,
“format” and “type”, that remain for the most part unchanged from the previous framework.