Most classrooms provide a blackboard, whiteboard or overhead projector for public viewing of information provided by the teacher. Replacing these presentation technologies with a computerized display makes capture relatively simple. We used a high quality Xerox Liveworks LiveBoard, a PC with a pen-sensitive, 67-inch diagonal screen. There are other less costly solutions, such as a pen-based computer attached to a LCD projector, or even projecting onto an upright digitizing tablet surface. Once computerized, the public display can be instrumented via software to log the time at which significant interactions occur.
None of the existing applications we had available for the LiveBoard allowed us to easily log pen events and convert the resulting annotated slides into a form (e.g., GIF) that was easily displayed on all Web browsers. Other similar commercial products suffered the same limitation. As a result, we had to write our own electronic whiteboard application, a Visual Basic prototype called ClassPad, whose interface is shown on the left side of Figure 1. We used ClassPad in the presentation-style HCI course to present prepared slides and allow for public annotation by the teacher. ClassPad preserves all annotations made to a series of prepared slides. In addition, ClassPad creates a time-stamped log of when the user navigates between slides and when each slide was annotated with the pen (defined as a pen-down followed by a pen-up sequence). This captured information is used in the post-production phase described in the next section.
We developed ClassPad for a presentation teaching style, but it is also appropriate for private notes or discussion-style classes in which the teacher simply wanted to have a blank surface upon which to write. In fact, several lectures in the HCI class used the private notes style. However, ClassPad was not appropriate for the public notes teaching style of the AI class, because the notes were displayed as Web pages. There is a serious registration problem that must be solved by the developer of the capture tool in order to provide persistent pen annotations for a markup language such as HTML. The rendered image (including the HTML text and any associated pen annotations) depends on characteristics of the bounding window, so it is much more difficult to register the pen annotation with the underlying text. Because of this difficulty, we did not capture pen annotations in the AI class. The only captured data in that class were the audio and video streams.
Future Computing Environments