Visualization of Shared Annotations

This section describes how shared annotations of other users can be accessed with CoScribe. The following scenarios provide several examples how individual learn- ing can be supported by shared annotations.

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Scenario 10 (Thoughts of other Persons). Sally has not well understood a particular issue. Reading the annotations of other persons helps her in getting the idea. In another course, a controversial topic was discussed. She is interested in what the other students think of this point and reads their annotations.

Scenario 11(Catching up on a Lecture). Sally was ill for some days and missed several lectures. She therefore carefully reads the annotations that her learning partners have made during the lectures.

Scenario 12(Collaborative Notetaking). Sally attends a course in which the handout is not very detailed. For this reason, the students take very extensive notes and sometimes there is not sufficient time to note everything which is important. Hence, Sally and two other students have agreed to jointly take notes. Each person is responsible for one particular aspect and notes everything which is related to this aspect. After the course, each of them completes his or her own notes with the notes of the two other students. This leads to more comprehensive notes.

In a traditional printed document, collaborative handwritten annotations are well visible because they are all made on the same physical document and the annota- tors can pay attention that their annotations do not overlap. Digitizing annotations enables the possibility to integrate annotations that are made on different physical copies of one document into one single digital version of the document. This stands in contrast to having a separate digital document for each physical copy. However, this poses the challenge of how the annotations of several users can be visualized in an aggregated view. As the users have different physical copies, their annotations might overlap because they are not aware of where other users make their annota- tions. An aggregated view would quickly become cluttered or even illegible when displaying a large number of possibly overlapping annotations of different users directly on the document. In the following, we discuss how we face this problem with digital and printed aggregated views.

Digital representation. The CoScribe viewer provides digital access to both own and shared annotations.

By separating the annotations of different users into different views, each of these views in itself becomes easier to read. The CoScribe viewer includes a single-user view for each member of the user’s learning group. This view displays the anno- tations of this specific user. Yet, this implies the need to manually switch between views of different users. This becomes particularly cumbersome in larger commu- nities.

In order to combine both one’s own and shared annotations in an integrated inte- grated multi-user view, one has to deal with overlapping annotations. We examined three techniques for addressing this problem. First, overlapping annotations could be moved to the margin of the documents. This implies the drawback of separating annotations from their context. Annotations that visually refer to the context (e.g.

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Figure 5.18: The CoScribe document viewer

underlinings, arrows, captions for printed elements) can become illegible. Second, the white spaces within a document page could be stretched to provide enough space for all annotations. However, this may result in very large document pages if the number of annotations is high and moreover overlapping annotations that refer to the same elements might loose their context, similarly to moving annotations to the margins.

CoScribe relies on a third technique. This consists in varying the size of individual annotations: collapsing annotations that are currently not relevant and expanding annotations that are in the user’s focus. In the CoScribe viewer, one’s own anno- tations are visualized as they are written on paper, whereas shared comments of other users are displayed in a condensed form. Instead of the annotation itself, a small icon is visualized at the position of the annotation (Fig. 5.18 (1)). This icon corresponds to the annotation category and varies in size according to the size of the annotation. When hovering with the mouse over the icon or tapping with the pen on it, the annotation is expanded and displayed at the correct position in its original size (Fig. 5.18 (2), annotation with grey background). The user can copy shared annotations considered especially relevant to his or her own script where they are displayed in their decompressed form like one’s own annotations. More-

Figure 5.19: A printout including annotations of two users

over, the symbols of annotations that are not considered relevant can be perma- nently removed from the view.

This has the advantage that the entire document remains readable and is dis- played at a reasonable size. However, not all annotations are visible at the same time. To address this issue, CoScribe includes a preview function, which displays all shared annotations in small size enabling an overview on all annotations. More- over, a view of all annotations made by a particular user is displayed when pressing a specific key while hovering over or tapping on an annotation of that user. This way, a single-user view displaying only the annotations of one specific user can be easily accessed.

The multi-user view and single-user views complement each other. While the multi-user view is rather used for getting an overview on all annotations on a slide, the single-user view is better suited when specifically focusing on the annotations of one specific user, for instance those of the instructor or those made by a student known for making helpful annotations.

Printed representation. Users can print documents including the annotations of one single user. This corresponds to the single-user view. Moreover, it is possible to print own annotations including those shared annotations of other users that were

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copied into the own script.

Printing the annotations of several users poses the same challenges as on the screen because annotations of different users might overlap. However, in contrast to screens, a dynamic expansion of collapsed annotations is not possible. For this reason, the print module generates a layout in which the document page is scaled down. Of each set of overlapping annotations, only one annotation is printed at its correct context position, while all other annotations are moved to the margins. Their context position is marked by a connecting line (see Fig. 5.19).

Scalability of multi-user visualizations. An important issue of views that integrate annotations from all users is their scalability to a large number of annotations and users. An evaluation with annotations made by students in real lectures (which is presented in more details in Section 7.2) supports the assumption that in a lecture scenario, the views scale well to a larger user community. Even in very large audi- ences, the average number of shared annotations per slide remains rather small.

Scalability clearly does not depend on own annotations. Similarly, annotations which are made by members of the user’s group do not have an influence, as the average number of members in a group is not affected by the size of the entire audi- ence. Hence, scalability only depends on public annotations. Our experiences show that in a lecture setting, only a very small fraction of annotations is published to the whole community. In our case this were 1.6 % of all annotations. In our lecture eval- uation, each student made an average of 0.59 annotations per slide. Assuming four members in a learning group, an average of 1.7 additional annotations are shared by these members. Public annotations of the entire audience average out at 0.9 an- notations for 100 participants and at 4.7 annotations for 500 participants. Hence, the total number of slides keeps small.

There are however some slides which are heavily annotated. In our evaluation, the most frequently annotated slide contains an average of 5.2 annotations per user. This “worst case” results in an average of 15.2 annotations shared by the own group and an additional 8 annotations or 41 annotations for 100 and 500 participants, re- spectively. These extremely high numbers apply only to a very small number of slides (the top 10 % of slides have more than an average of 2.8 annotations per user). In order to cope in these situations with a too large number of public annota- tions, these annotations could be automatically filtered. While personal and shared group annotations are visualized as discussed above, only these public annotations that have been implicitly classified as relevant by members of the author’s group are displayed to the entire audience.