The International Children's Digital Library
First Monday

The International Children's Digital Library: Description and analysis of first use by Allison Druin, Benjamin B. Bederson, Ann Weeks, Allison Farber, Jesse Grosjean, Mona Leigh Guha, Juan Pablo Hourcade, Juhyun Lee, Sabrina Liao, Kara Reuter, Anne Rose, Yoshifumi Takayama, and Lingling Zhang

The International Children's Digital Library: Description and analysis of first use by Allison Druin, Benjamin B. Bederson, Ann Weeks, Allison Farber, Jesse Grosjean, Mona Leigh Guha, Juan Pablo Hourcade, Juhyun Lee, Sabrina Liao, Kara Reuter, Anne Rose, Yoshifumi Takayama, and Lingling Zhang
We present the first version of the International Children's Digital Library (ICDL). As a five-year research project, its mission is to enable children to access and read an international collection of children's books through the development of new interface technologies. This paper will introduce the ICDL and an initial analysis of the first seven weeks of the ICDL's public use on the Web.


The current ICDL software
Analysis of user log data




The current ICDL software

The International Children's Digital Library (ICDL) was launched on 18 November 2002 and currently includes 181 books from 14 countries (e.g., Egypt, Croatia, Singapore, South Africa, Australia, New Zealand, United States and more) in 20 languages. The actual software technologies are based on previous NSF DLI-2 funded research in children's interface development that was conducted at the University of Maryland (Druin et al., 2001; Revelle et al., 2001). From 1999-2002, we researched and developed a visual interface that supports young children (ages seven-nine years) in querying, browsing, and organizing multimedia information. This initial project had multimedia resources focused on animal information donated by the Discovery Channel and the Patuxent Wildlife Research Center. It was used by children at Yorktown Elementary School in Bowie, Maryland in order to test and refine the interface. By building on this research foundation, and generalizing to a broader library collection and audience of children, ICDL research prototypes have been quickly deployed.

A unique aspect of this work is the process of collaboration and partnership that has been established (Druin et al., 2001). Interdisciplinary researchers from computer science, information studies, education, art, and psychology work together with children (ages 7-11) to design this new library. Children's ideas are heard throughout the entire technology design process. To make this a reality, children work in the labs as researchers twice a week during the school year, and two intensive weeks over the summer. Together this interdisciplinary and intergenerational team brainstorms, sets project directions, tests new ideas, and implements technologies (video of team activities at

In addition to this partnership for interface development, the ICDL has also established partnerships with national libraries, public library systems, professional associations, commercial publishers, authors, illustrators, and school districts around the world. Collection development guidelines are being jointly created, materials identified and digitized, and fair use models are being explored. Approximately 40 percent of the books in the current collection are within copyright and were provided by contributors with specific restrictions. Some publishers or authors have agreed to donate their materials only if they are encrypted for book viewing, others have offered their books on a limited basis. All are interested in understanding the market potential for such a delivery mechanism.

The current ICDL software is written in Java and relies upon Sun's freely available Java 2 platform, currently available for Windows, Solaris, Linux and Mac OS. It is built using the Jazz toolkit for Zoomable User Interfaces (Bederson et al., 2000). The software is deployed with Java Web Start technology that enables a user to download, install, and launch the software with a single click on a Web page link (once Java is installed). The software may then be launched either from the Web page, or a desktop icon. We are currently working on an HTML-only version of the ICDL which we plan on deploying in the summer of 2003.

Most books are stored unencrypted on a Web server in jpeg format and accessed directly through the Java client software. However, some books are encrypted according to publisher's requests and are served with Adobe Content Server. Those books are accessed through our application's visual search system, but are read with the freely available commercial Adobe eBook Reader application.

The ICDL software application currently supports children with highly visual interface technologies to find and read books. A short description of the current interface functionality follows.

Finding books

There are two ways to access and retrieve books. The first considers books by geography. There is a globe area that enables children to spin the globe and select a region (e.g., Africa, Europe, Asia, etc.). From this process, the search results provide a subset of the collection that is about the region, set in the region, or written by an author from the region (Figure 1).

Figure 1: Searching for books using the globe interface.

A richer way to find books is through the visual search interface. Thirteen top-level search categories were chosen based on research with children and librarians concerning how children want to look for books (Figure 2). The categories include: the subject of the book; the types of characters in the book, if it is "true" or "make-believe"; how well it is rated by other children; how it makes children feel (e.g., "I want to find a book that makes me happy"); the shape; and the color of the book's cover.

Figure 2: The visual search categories.

Clicking on one of these icons zooms in to reveal the possible attributes of that field. Clicking on one those attributes performs a search on that attribute. The icon is smoothly moved to the "search caterpillar," which represents the current search. If multiple attributes are chosen, a Boolean intersection is performed between those attributes. The search results are presented visually through book covers in the search result area (Figure 3). Clicking on the search results brings the child to that area where they can then use a "Zoomable User Interface" to visually explore those results.

Figure 3: The visual search results area. This shows all books with animals grouped by subject.

The search results are shown using an embedded version of PhotoMesa (Bederson, 2001). PhotoMesa presents groups of images in rectangles which can then be examined more closely. Clicking on a group zooms into the group, and clicking again zooms in further to individual books.

When a single book is clicked on, the "book preview" page is shown which includes metadata about the book, including title, author, date, language, publisher, contributor, page count and summary. From here, the book can be read with one of the four book readers.

Book reader prototypes

There are currently three book readers that we developed (Hourcade et al., in press) and Adobe's eBook Reader for books that the contributor required to be encrypted. Children may use the reader with which they are they most comfortable (except for encrypted books which currently requires Adobe eBook Reader). Our traditional reader is most similar to traditional commercial readers. It shows one page at a time with simple forward and backward navigation buttons. There are controls for the visual "skin" of the controls. Users can also specify the orientation of the controls (horizontal or vertical) and whether the pages are shown one at a time, or in a two-page spread.

All pages are deployed with a 1024x768 pixel jpeg image, but when zoomed in (with the magnifying glass icon), an image twice that resolution is downloaded in the background

The "comic strip" book reader presents a zoomed out view of the visual book pages — oriented in horizontal strips like a comic strip (Figure 4). To read sequentially, a user simply presses the right arrow (or page down key). The interface smoothly zooms into the first page, and then animates to the next page in order upon subsequent arrow presses. At any time, the user may press the "zoom out" button to return to the starting overview page, and then click on any page to go directly to it, no matter what the page order of the book. The page borders are colored to indicate whether a page has been visited or not. The goal of this reader is to support simple overviews without getting in the way of traditional linear access.

Figure 4: The comic strip book reader.

On the other hand, the "spiral" reader is more dynamic. Its goal is to provide an experience like flipping through the pages of the book to quickly examine the book's content. It presents the pages of the book in linear order with a "focus" that is larger than the other pages, and a tail that shrinks (Figure 5). Like the comic strip reader, simple linear access is provided by the arrow buttons (or normal keyboard shortcuts), at which point the focus page is smoothly zoomed up to fill the screen. Going to the next page simultaneously shrinks the focus page down, rotates the spiral to focus the next page, and zooms up that next page. At any point, the zoom out button can be pressed to shrink the focus page, and then the user can click on any page in the spiral to spin the spiral so that page comes to the focus spot.

Figure 5: The spiral book reader.



Analysis of user log data

In an attempt to try and understand how the library is actually being used by the general Web public, we have analyzed log data. The results of this initial analysis are briefly presented.

During the first seven weeks of public use, log data was collected that suggested who was accessing the software, what search methods were used, and what books were accessed. For a shorter period of time, log data was collected on the use of the book reader interfaces. The log data was analyzed and the results are summarized below. This log analysis was performed using the commercial Sawmill log analysis product ( We use the term "visitor" to mean Web accesses from unique IP addresses over the period of the analysis and "page view" to mean a specific Web page accessed by any client. Each "session" is defined to mean access from a unique IP address with no inactive period greater than 30 minutes. All numbers are rounded.

Over the first seven weeks of use 10,000 visitors successfully ran the ICDL software. Of those users, the majority were from the United States, followed by Canada and Taiwan:

North America
7,000 visitors
(67 percent)
1,700 visitors
(17 percent)
1,200 visitors
(12 percent)
300 visitors
(2 percent)
South America:
100 visitors
(1 percent)
15 visitors
(<1 percent)

We found that 79 percent of users looked for books by using the visual search (Category) interface, while 21 percent used the Globe interface. Sixty-eight percent of category searches were on a single category with 32 percent on two or more categories. The top five single category searches were:

Books for three to five year olds
Books in English
Books for six to nine year olds
Books about imaginary beasts and creatures
Books rated with five stars

For the users that searched by geographic area with the globe interface, they searched for books by continent as follows:

North America
29 percent
24 percent
23 percent
South America:
10 percent
8 percent
6 percent

During the initial seven week period, 36,000 total books were accessed (not including books that were read multiple times once they were downloaded. We are unable to track this information.) The most popular book was Axel the Freeway Cat (Hurd, 1981). The popularity of this title may have been due to the fact that it was mentioned in numerous articles that appeared in press coverage of the ICDL launch. The next most popular books were Sun Flight (McDermott, 1980), an in-copyright book contributed to the collection by Caldecott Award winning author, Gerald McDermott; Where's the Bear? (Brueghel, 1997), a simple story in multiple languages donated by the Getty Foundation ; and Going Downtown and Other Rhymes (Choo, 1996), a book about life in Singapore, donated by the Getty Foundation.

As for the books that were requested by publishers to be encrypted, the total number of books accessed was 1,075 (again, not including locally cached accesses). The most popular book accessed through the Adobe Book Reader was How Do Dinosaurs Say Good Night? (Yolen, 2000) followed by Is Your Mama A Llama? (Guarino, 1989) and When Sophie Gets Angry — Really, Really Angry (Bang, 1999). All of these books were contributed to the ICDL by Scholastic, Inc. The total number of books accessed through the Adobe Book Reader was considerably less (19 percent) than those accessed through the other three readers.

During a three week analysis of the other book readers, the standard book reader was used 69 percent of the time, the comic book reader was used 16 percent, and the spiral book reader was used 15 percent. Using these readers, 431,000 pages were accessed by all users. On average, each visitor looked at 1.5 books, and this number stayed relatively constant throughout this period. Most visitors viewed only one book, but more than 100 visitors read ten or more books. End of article


About the Authors

Allison Druin is the Project Director for the ICDL at the University of Maryland. She is an Assistant Professor in the College of Information Studies and Human-Computer Interaction Lab, where she leads research teams in developing and evaluating new technologies for children.

Benjamin B. Bederson is the Technology Project Director for the ICDL and is the Director of the Human-Computer Interaction Lab. In addition, he is an Assistant Professor in the Computer Science Department where he explores and develops novel approaches for visualizing and interacting with electronic information.

Ann Weeks is the ICDL Director for Collection Research and Use and is a Professor of the Practice in the College of Information Studies and the Human-Computer Interaction Lab. Her research interests focus on school library media programs and how new technologies can change strategies for teaching and learning.

Allison Farber is a staff multimedia specialist at the Human-Computer Interaction Lab and created most of the artwork for the ICDL. She also works with our child design partners on design issues.

Jesse Grosjean is a staff programmer at the Human-Computer Interaction Lab and sets up much of the data analysis software for the ICDL. He also contributes to the development efforts of the "zoomable user interface" toolkits that are used for the ICDL.

Mona Leigh Guha is a graduate student in the College of Education's Department of Human Development. She works with our child design partners, tests our software with other child users, and helps other testing sites.

Juan Pablo Hourcade just finished his Ph.D. at the University of Maryland's Computer Science Department. He developed the base user interface technology for searching and viewing books, as well as the information retrieval architecture.

Juhyun Lee is a graduate student in the College of Education's Department of Human Development. She works with our child design partners and tests our software with other child users.

Sabrina Liao is the ICDL Webmaster and a staff multimedia design specialist in the Human-Computer Interaction Lab. She creates art, videos, and works on visual design problems.

Kara Reuter is a graduate student in the College of Information Studies. She works with our child design partners, organizes user testing for the ICDL, tests the ICDL with children, and thinks about ways to organize the ICDL collection to make it easier for children to find books to read.

Anne Rose is a Faculty Research Assistant in the Human-Computer Interaction Lab. She designs and manages the database that holds the books in the ICDL collection and also coordinates digital book processing and cataloguing efforts.

Yoshifumi Takayama was a visiting researcher from Toshiba Corporation from 2001-2002. He worked on the book reader software and the help system.

Lingling Zhang is a graduate student in the University of Maryland's Computer Science Department. She developed the caching technology that helps ICDL retrieve books more efficiently and currently works on various issues concerning user searching and browsing.



We gratefully acknowledge the thousands of users of the ICDL. Without their interest and voluntary use of the software, we could understand very little about the software we have created. We are also indebted to our partners at the Internet Archive, particularly Brewster Kahle and Brad Tofel, who initially hosted the ICDL site, and to Jane White and Jessica Anthony, who are spearheading our collection development and partnership efforts.

In addition, we would like to thank the countless children, teachers, and librarians who have contributed to the design of our new interface technologies, and the numerous national libraries, publishers, authors, and illustrators from around the world who have donated books to the ICDL collection. And finally, we would like to thank the National Science Foundation for our ITR grant, and the Institute of Museum and Library Services for our National Leadership grant. Without this generous funding, our research would not be possible.



M. Bang, 1999. When Sophie Gets Angry — Really, Really Angry. New York: Blue Sky Press.

B.B. Bederson, 2001. "PhotoMesa: A Zoomable Image Browser Using Quantum Treemaps and Bubblemaps," UIST 2001, ACM Symposium on User Interface Software and Technology, CHI Letters, volume 3, number 2, pp. 71-80.

B.B. Bederson, J. Meyer, and L. Good, 2000. "Jazz: An Extensible Zoomable User Interface Graphics Toolkit in Java," UIST 2000, ACM Symposium on User Interface Software and Technology, CHI Letters, volume 2, number 2, pp. 171-180.

J. Brueghel, 1997. Where's the Bear? Los Angeles, Calif.: Getty Foundation Publications.

K.K. Choo, 1996. Going Downtown and Other Rhymes. Singapore: NTUC Childcare Cooperative Ltd.

A. Druin, B.B. Bederson, J.P. Hourcade, L. Sherman, G. Revelle, M. Platner, and S. Weng, 2001. "Designing a Digital Library for Young Children: An Intergenerational Partnership," In: Proceedings of Joint Conference on Digital Libraries, 24-28 June 2001, Roanoke, Va. (JCDL 2001). New York: ACM Press, pp. 398-405.

D. Guarino, 1989. Is Your Mama A Llama? New York: Scholastic, Inc.

J.P. Hourcade, B.B. Bederson, A. Druin, A. Rose, A. Farber, and Y. Takayama, in press. "The International Children's Digital Library: Viewing Digital Books Online," In: Interacting With Computers.

T. Hurd, 1981. Axel the Freeway Cat. New York: Harper & Row.

G. McDermott, 1980. Sun Flight. New York: Four Winds Press.

G. Revelle, A. Druin, M. Platner, B.B. Bederson, J.P. Hourcade, and L.E. Sherman, 2001. "Young Children's Search Strategies and Construction of Search Queries," Journal of Science Education and Technology, volume 11, number 1, pp. 49-57.

J. Yolen, 2000. How Do Dinosaurs Say Good Night? New York: Blue Sky Press.

Editorial history

Paper received 1 May 2003; accepted 4 May 2003.

Contents Index

Copyright ©2003, First Monday

Copyright ©2003, Allison Druin

Copyright ©2003, Benjamin B. Bederson

Copyright ©2003, Ann Weeks

Copyright ©2003, Allison Farber

Copyright ©2003, Jesse Grosjean

Copyright ©2003, Mona Leigh Guha

Copyright ©2003, Juan Pablo Hourcade

Copyright ©2003, Juhyun Lee

Copyright ©2003, Sabrina Liao

Copyright ©2003, Kara Reuter

Copyright ©2003, Anne Rose

Copyright ©2003, Yoshifumi Takayama

Copyright ©2003, Lingling Zhang

The International Children's Digital Library: Description and analysis of first use by Allison Druin, Benjamin B. Bederson, Ann Weeks, Allison Farber, Jesse Grosjean, Mona Leigh Guha, Juan Pablo Hourcade, Juhyun Lee, Sabrina Liao, Kara Reuter, Anne Rose, Yoshifumi Takayama, and Lingling Zhang
First Monday, volume 8, number 5 (May 2003),

A Great Cities Initiative of the University of Illinois at Chicago University Library.

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