Students at Esperanza High School in the Placentia-Yorba Linda Unified School District were the first to sample a new experimental approach designed to measure students' understanding of content in complex problem spaces. Students with experience solving the HAZMAT chemistry simulation were shown rapid sequences of test results from the problem and asked whether or not the sequence represents a successful approach to a particular solution. Each image is displayed for only 1.5 seconds and each stack of test results contained between six and 22 images. The sequence repeats until the student makes a decision. Students were generally able to make dozens of decisions in the time allotted. Results showed that the groups became faster with each stack and accuracy increased.