Elementary-age children are among the largest user groups of computers and the Internet, so it is important to design searching and browsing interfaces to support them. However, many interfaces for children do not consider their skills and preferences. Children can perform simple, single item searches, and are also capable of conducting Boolean searches involving multiple search criteria. However, they have difficulty creating Boolean searches using hierarchical structures found in many interfaces. These interfaces often employ a sequential presentation of the category structure, where only one branch or facet at a time can be explored. This combination of structure and presentation keeps the screen from becoming cluttered, but requires a lot of navigation to explore categories in different areas and an understanding of potentially abstract high-level categories.

Based on previous research with adults, I believed that a simultaneous presentation of a flat category structure, where users could explore multiple, single-layer categories simultaneously, would better facilitate searching and browsing for children. This method reduces the amount of navigation and removes abstract categories. However, it introduces more visual clutter and sometimes the need for paging or scrolling. My research investigated these tradeoffs in two studies comparing searching and browsing in two interfaces with children in first, third, and fifth grade. Children did free browsing tasks, searched for a single item, and searched for two items to create conjunctive Boolean queries. The results indicate that a flat, simultaneous interface was significantly faster, easier, likeable, and preferred to a hierarchical, sequential interface for the Boolean search tasks. The simultaneous interface also allowed children to create significantly more conjunctive Boolean searches of multiple items while browsing than the sequential interface. These results suggest design guidelines for others who create children's interfaces, and inform design changes in the interfaces used in the International Children's Digital Library.