COMPUTER-AIDED DESIGN (CAD) LOGS PROVIDE FINE-GRAINED EMPIRICAL DATA OF STUDENT ACTIVITIES FOR ASSESSING LEARNING IN ENGINEERING DESIGN PROJECTS. HOWEVER, THE INSTRUCTIONAL SENSITIVITY OF CAD LOGS, WHICH DESCRIBES HOW STUDENTS RESPOND TO INTERVENTIONS WITH CAD ACTIONS, HAS RARELY BEEN EXAMINED. FOR THE LOGS TO BE USED AS RELIABLE DATA SOURCES FOR ASSESSMENTS, THEY MUST BE INSTRUCTIONALLY SENSITIVE. THIS PAPER REPORTS THE RESULTS OF OUR SYSTEMATIC RESEARCH ON THIS IMPORTANT TOPIC. TO GUIDE THE RESEARCH, WE FIRST PROPOSE A THEORETICAL FRAMEWORK FOR COMPUTER-BASED ASSESSMENTS BASED ON SIGNAL PROCESSING. THIS FRAMEWORK VIEWS ASSESSMENTS AS DETECTING SIGNALS FROM THE NOISY BACKGROUND OFTEN PRESENT IN LARGE TEMPORAL LEARNER DATASETS DUE TO MANY UNCONTROLLABLE FACTORS AND EVENTS IN LEARNING PROCESSES. TO MEASURE INSTRUCTIONAL SENSITIVITY, WE ANALYZED NEARLY 900 MEGABYTES OF PROCESS DATA LOGGED BY OUR ENERGY3D CAD SOFTWARE AS COLLECTIONS OF TIME SERIES. THESE TIME-VARYING DATA WERE GATHERED FROM 65 HIGH SCHOOL STUDENTS WHO SOLVED A SOLAR URBAN DESIGN CHALLENGE USING ENERGY3D IN SEVEN CLASS PERIODS, WITH AN INTERVENTION OCCURRING IN THE MIDDLE OF THEIR DESIGN PROJECTS. OUR ANALYSES OF THESE DATA SHOW THAT THE OCCURRENCE OF THE DESIGN ACTIONS UNRELATED TO THE INTERVENTION WERE NOT AFFECTED BY IT, WHEREAS THE OCCURRENCE OF THE DESIGN ACTIONS THAT THE INTERVENTION TARGETED REVEALS A CONTINUUM OF REACTIONS RANGING FROM NO RESPONSE TO STRONG RESPONSE. FROM THE TEMPORAL PATTERNS OF THESE STUDENT RESPONSES, PERSISTENT EFFECTS AND TEMPORARY EFFECTS (WITH DIFFERENT DECAY RATES) WERE IDENTIFIED. STUDENTS' ELECTRONIC NOTES TAKEN DURING THE DESIGN PROCESSES WERE USED TO VALIDATE THEIR LEARNING TRAJECTORIES. THESE RESULTS SHOW THAT AN INTERVENTION OCCURRING OUTSIDE A CAD TOOL CAN LEAVE A DETECTABLE TRACE IN THE CAD LOGS, SUGGESTING THAT THE LOGS CAN BE USED TO QUANTITATIVELY DETERMINE HOW EFFECTIVE AN INTERVENTION HAS BEEN FOR EACH INDIVIDUAL STUDENT DURING AN ENGINEERING DESIGN PROJECT.