Educators have recognized the limitations of artificial assessments and called for more authentic assessments of student performance, i.e., assessment that is contextualized. In the field of movement education, teachers have typically tended to evaluate their students by administering skill tests, categorizing children for their developmental level on fundamental skills, and watching students play in games. However, skill tests are not very authentic, and game playing is only authentic if the context is specified. Motor development scholars increasingly use a new model of movement that can help teachers design authentic assessment. The model takes into consideration person, task, and environment. The paper presents examples of using a movement model based on Herkowitz' Task Analysis to conduct authentic assessment of two tasks (kicking for accuracy and throwing for distance). The system was designed to analyze a movement task by specifying characteristics of the environment and their levels on an easy-to-hard or simple-to-complex continuum. (Contains 11 references.) (SM)