Abstract: The Calipers project developed and studied a new generation of simulation-based assessment systems. The project aimed to demonstrate the potential of technology-and simulation-based assessments to provide high-quality evidence of complex performances for science tests that address accountability or formative goals. End-of-unit, benchmark assessments for the topics of ecosystems and for forces and motion were developed to test national science standards at the middle school and secondary levels. Technical quality evidence documented the alignment of the assessments with national science standards, expert reviews of content and item quality, cognitive analyses of students thinking-aloud, and analyses of teacher and student data gathered from classroom pilot testing. The project broke new ground in harnessing the affordances of technology to transform what, how, when and where science learning is assessed and to gather evidence of students' connected science knowledge and extended inquiry not well measured by traditional paper-based tests
