The Barrierfree Learning Object Structure
Educational videos or films have been a powerful mechanism for teaching a large range of topics for a number of decades. They have been successful in engaging learners when other teaching tools do not. Video is the type of rich media broadband networks are intended for. One disadvantage of video is that it is inaccessible to learners with sensory disabilities and it forces the learner to progress through the content in a prescribed sequence and at a prescribed pace. Of the media types available for on-line learning, video is also the least amenable to transformation and customization. The Barrierfree project chose this most challenging media type to demonstrate the techniques and learning advantages of creating inclusive on-line learning environments.
Due to legislation in a number of countries, many videos or films intended for broadcast are accompanied by verbatim closed captions. Captions are a text transcript of what is spoken or heard in a video or film. These captions are precisely synchronized to the video. A number of films or videos also have accompanying video descriptions. These are verbal descriptions of what is seen in the video. These descriptions form a synchronized audio track that intersperses the descriptions in the quiet sections of the videoÕs original audio track. The Barrierfree project uses both the verbatim caption and the transcript of the video description to create a framework for the video content. This text track framework is used to enrich the film and make it interactive by acting as a backbone that indexes the video and links enriching content to the video. Supporting content, interactive exercises, definitions of terms, self evaluations, background material and learner scaffolds are linked to the captions and video descriptions. Thus if a learner viewing a physics video encounters a term they do not understand, they can click on the term in the caption, view a definition of the term, experience an interactive exercise of the concept, navigate back to the point in the video when the term was introduced, or reinforce their understanding of the concept in a number of other ways.
The text-track framework is also the basis for re-purposing a lesson. An educator who wishes to adapt an existing enriched video for the learning needs and curriculum requirements of their class can do so by swapping or adding the auxiliary content. Caption tracks at reduced reading levels or in alternative languages can be added. Linked exercises or supporting material can be replaced with local examples or examples more relevant to the students. Links to self evaluations appropriate to the curriculum requirements can be added. Teacher annotations in audio, text or graphic form can be added.
The learning object repository developed in the Barrierfree project supports this repurposing and customized viewing of the enriched video content by maintaining information about the learning content in two forms: the assembly object and the content object. The assembly object records how the original video and the enriched content are assembled. The content objects are the reusable components that can be used in assembling the lesson. A number of derivative assembly objects can be stored in the repository, so that when an educator customizes the original enriched video their version of the assembly object is stored as well as the original.
All the Barrierfree tools also support the personalization of the learning content. The learner can specify how they wish the content to be displayed, which content components they wish displayed and how they wish to control the content.
As well as accessibility, the Barrierfree project is committed to interoperability. The technologies were developed using Java, and data was encoded using XML. Figure 1 provides an overview of the components that were developed, and their interactions. The underlying system consists of a core set of Java classes for representing learning objects and their metadata, a set of Java classes for representing the captions (which act as the backbone for the presentation) and other time-based information such as the video descriptions, and graphical overlays, and a set of Java classes for maintaining the learner preferences.
Figure 1 Software packages and interdependencies
