The Effects of Parent-Child Activity Program on PA of Children With Cancer

The goal of this clinical trial is to test the effect of Parent-Child activity program on physical activity of children with cancer. The main question it aims to answer is: * Whether the Parent-Child activity program has effectiveness for children with cancer on their physical Activity, Physical Activity Self-Efficacy, Physical Activity Enjoyment, Family Support, and for parents on Physical Activity based on the Youth Physical Activity Promotion Model. Participants will: * Receive a handbook on information related to physical activity and Parent-Child physical activity when the child is undergoing treatment. * Participate in Parent-Child activities, such as throw ball catch game, which are organized by the professionals. * Parents or/and children receive subscriptions on physical activity through WeChat, including the benefits of physical activities and Parent-Child activities, common physical activities and Parent-Child activities, and follow-up video. Researchers will compare control group to see if there are differences between usual care on physical activity and Parent-Child activity program