The rising number of foreign residents in Japan has caused the number of children with foreign backgrounds in Japanese schools to increase. The present Japanese education system does not adequately support children whose mother language is not Japanese, and their educational problems have turned into social issues. We have conducted an action research project in collaboration with several schools and one university to determine how to develop a support system through online media that would soften the impact of the COVID-19 pandemic. We argue that language assessment is the key to driving the project and sharing the results of the assessment analysis with all project participants works effectively to promote collaboration between schools, families, and the university.