How can a child send a message to the teacher when he goes to school with a fever?

Tell the truth. General schools will report the health status of their teachers and students daily according to the requirements of epidemic prevention and control. Your child has a fever, which is a typical disease. I suggest you send your child to see a doctor first and ask the teacher for leave at the same time. Otherwise, the child will be sent to school with a cold and the consequences will be very serious. Maybe the school will inform you to take the child to the hospital as soon as possible. If you do this, you will be very passive.