One is the Virtual Reference Desk's (VRD) Learning Center (http://vrd.askvrd.org/search.asp), and the other is a yearly, week-long, digital reference service sponsored by the National Science Foundation (NSF) during Excellence in Science, Technology, and Mathematics Education Week (ESTME) (http://www.estemeurlhere.com).
Both the Learning Center and the ESTME digital reference services provided pull-down menus so users could describe their roles (for example, student, teacher, parent) and the uses to which they would put the answers (for example, written report, science fair project, just curious.) Only questions that were asked by "students" who marked the "just curious" category were kept in the database.
Questions from students in grades K-5 were coded "Elementary Student." Questions from students in grades 6-8 were coded "Middle School Student," and questions from students in grades 9-12 were coded "High School Student." A total of 114 unique questions (35 from the Learning Center and 79 from the ESTME service) remained.