Can I ask my child's exam ranking by SMS?

Of course. When the results come out, you can send a text message or a private letter to the teacher. Never ask the teacher about your child's grades in the WeChat group. Because the education authorities now stipulate that teachers are not allowed to publish the test scores of class students on WeChat groups and other tools, nor are they allowed to rank students. So if parents want to ask about their grades, they can contact the teacher through private chat.