One of the new measures developed as part of the Apple Classrooms of Tomorrow (ACOT) program is described. The ACOT project examines the impact of access to educational technology on the kindergarten through grade 12 classroom environments. The new measure is a technology-based classroom observation instrument for documenting the impact of technology on classroom instruction. The instrument uses a time-sampling procedure and is organized for recording in timed intervals using a machine-scannable form. Observers code a few key indexing variables for the activity period observed as follows: (1) subject area; (2) number of students assigned; (3) classroom observation; (4) adult roles (directing instruction, facilitating instruction, management and discipline, and not present); (5) symbol systems serving key instructional functions; (6) symbol systems that students use; (7) length of responses expected of students; (8) level of processing expected of students; (9) resources in use; and (10) students' responses to the activities. The instrument is currently used in documentation of high technology access classrooms (a database with 12 total hours observed in language arts and 6.1 hours in mathematics) and in documentation of changes in instructional practices associated with technology use over time (observations at elementary school and secondary school sites). The instrument's usefulness will ultimately depend on coordination with other data gathering techniques. Two tables present study findings, and 32 bar graphs provide examples of the "snapshot" graphical displays generated by the instrument. A 35-item list of references is included. (SLD)