Dr. Ju-Tang Hsiao is an Assistant Research Fellow at the Research Center for Testing and Assessment, NAER, Taiwan. He obtained his PhD in physics from National Taiwan University. His thesis focused on many-body dynamic theories in relativistic equations of motion. After completing his degree, he served as a Field Artillery Officer in the army. Subsequently, he was a Postdoctoral Fellow at the Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica. At the IAMS, he conducted research pertaining to spin polarization, orientation, and coherence effects in photoionization processes. In 2012, Dr. Ju-Tang Hsiao moved to the Research Center for Testing and Assessment, NAER. His research interests include not only science but also science learning and teaching. His　primary interest is in how formative assessment can be used to obtain the information needed to help students learn science in the classroom and to further apply the concepts of formative assessment to student learning and teacher instruction.