There is no point in complaining about our children to somebody else. Even if our child is not doing good in a particular subject, it is better to sit with him and observe what are the mistakes he is committing and advise him how to avoid. You should do that privately in your house. Otherwise separately you can meet the teacher and talk to him about your child and see that he will improve. More than that you can arrange tuition for that subject. In stead of that if you chide him , the child will definitely get hurt. If you want to praise any body you can do that in a gathering so that the individual will get motivated. If you want to advise, caution or warn anybody you do it desperately but not in a group. It is always better for a person to take your advises positively.