Collaborative Environments: Accessibility and Usability for Users with Special Needs - Community-Built Databases: Research and Development - page 329

13.4.1 Educational Objects

Educational objects are multimedia objects describing notions represented through
different media - text, image, sound - that can be described at three levels of
complexity: complete , summary , and simplified . Figure 13.1 shows an example of
these three levels for an educational object describing a leaf. For the leaf, the three
descriptions (taken from Wikipedia) are given, each one providing a different level
of detail. Specifically, the simplified description preserves essential concepts that
are expressed with a simpler structure of the sentences and a controlled vocabulary
and are thought for students with cognitive difficulties. Notice that simplified
descriptions can also be useful for students who are learning a foreign language
and possess a temporarily reduced vocabulary.
With this design choice, we have addressed guideline 3.1 of WCAG 2.0, and
especially number 3.1.5 Reading Level: “When text requires reading ability more
advanced than the lower secondary education level after removal of proper names
and titles, supplemental content, or a version that does not require reading ability
more advanced than the lower secondary education level, is available”.
Besides textual descriptions, audio descriptions can be included. This alternative
can be useful when the screen reader cannot reach the same quality of human
reading (e.g., for reading a poem in ancient Greek).
An educational object is stored within VisualPedia as an XML document that
replaces the textual content contained in the text attribute of the Mediawiki page
table. This XML document contains the descriptions of the object at the three levels
of complexity plus the bibliography reference and optional links to vocal descrip-
tions. Images and sounds are stored in the VisualPedia Image table. Tags are
introduced in the XML document to distinguish the role (an object or part of a
description) of the image/sound within the educational object. Moreover, in the
Image table, the values of longDesc and alt attributes required for image

1. . In botany, a leaf is an above-ground plant organ specialized for photosyn-

thesis. For this purpose, a leaf is typically flat (laminar) and thin. There is continued
debate about whether the flatness of leaves evolved to expose the chloroplasts to more
light or to increase the absorption of carbon dioxide. In either case, the adaption was
made at the expense of water loss. Leaves are also the sites in most plants where tran-
spiration and guttation take place. Leaves can store food and water, and are modified in
some plants for other purposes. The comparable structures of ferns are correctly referred
to as fronds. Furthermore, leaves are prominent in the human diet as leaf vegetables.
2.

Complete

. A leaf is a plant organ specialized for photosynthesis and is typically flat
and thin. Leaves are also the sites in most plants where transpiration and guttation take
place. Leaves are prominent in the human diet as leaf vegetables.
3. Simplified. If you look at the tree in the park, it is full of flat leaves that can be of
different colours depending on the season. The tree uses them for many purposes, for
example for converting carbon dioxide into sugars using the energy from sunlight. There
are types of leaves that humans can eat.

Summary

Fig. 13.1 Three different textual descriptions of the leaf educational object