Abstract
Many studies regarding health and environment quality showed the importance of natural environment to children's health and physical activities. Schoolyard is the main place where children do physical activities during a day. However, there is a lack of domestic studies exploring the relationship between the degree of natural schoolyard environment and the amount of children's physical activities. This study used Seattle Green Factor as indicator, sampled one school from each of the different Urban Planning District Elementary School levels, according to the number of classes and area of the campus. Common surface patterns of the four schools are collected through aerial photographs and field studies, and expert assessment is used to evaluate the green factors' effectiveness of common surface patterns. GPS and heart rate monitoring watches are used as measure instruments, along with questionnaires to record children's background information, time of outdoor activity, and frequency. Physical activity questionnaire this study developed combined with schoolyard green factor index are analyzed together. The main results of this study are as following: 1. Green factor index do not have quantitative differences in children's total physical activity time and some activities. 2. Children studying in schools with high green factor level have higher participation rate in physical education class, longer activity time during recess, and different levels of physical activity time, which all have positive influence on health. 3. Besides having a lot of trees, elementary schools which showed a positive relation between schoolyard green factor and physical activity have partially open surface pattern, and big proportions of playground and lawn areas, which all help promote physical activities. 4. Children's physical activities mostly happen in school, but the amount of physical activities happened during recess is still not enough.