Though we are prototyping the notebook as a distinct application, it can be accessed directly through the Water Quality Simulator's web interface. The notebook is designed to help teachers help students make their thinking explicit as they analyze different types of relationships between water quality variables. It provides a mechanism for the teacher to scaffold student learning by posing carefully crafted questions tailored to the specific problem at a given step in the exploration: such as evaluating the evidence for two variables being linked, and posing a hypothesis as to what causal factors link them. Also, the notebook supports authentic, performance-based assessments of what students are learning as they proceed stepwise through the simulator.

Through the database underlying the digital notebook developers and participating teachers can embed instructions and questions, and students can enter their thoughts and observations. User administration of the notebook Permissions for login to the notebook application can be set up for different types of users. When teachers login, they can set logins and passwords for a class and for student workgroups.

Each question evoked through the notebook is assigned a pair of keywords from the keyword classes in the datatase program, i.e., indicator, land use, and management practice: for example, nitrogen, agriculture, buffer strips, respectively. Questions might be posed to trigger comparisons between a chosen indicator in two land use areas , or about the quantitative (and potentially causal) relationship of one variable to another within a particular area. Teachers can add their own questions to the database, keying them to indicators and land use.

The user interface supports filtering and search capabilities so that only questions linked to selected keywords appear in the notebook. Such questions, which are evoked when the notebook is brought up via a link from the web interface to the simulator program, are linked to the graphical display of the variables selected by the student. Students can enter, delete or edit their own observations, thoughts and answers, but no one else's. Nor can they alter another students' entries. In contrast to students, the teacher can access the notebook database directly in order to select questions from a pre-developed list or create or edit his/her own questions.

The overall design of the notebook and its supporting database is flexible, thus allowing the development and editing of keyword classes for notebooks linked to other web-based simulations.