If your teenager does poorly on a school test, do not express your disappointment, shame or anger.
Instead, ask you teenager if she thinks that there is a reason behind the poor score, and if there is anything that you or her teacher can do to help.
Acknowledge your teenager's good behaviour, well-written school papers and overall effort.
Suggest ways that your teenager can improve a fault, but don't say it judgmentally.
Support and offer understanding for your teenager, even if her performance does not always meet with your expectations.
Appropriate praise will encourage your teenager to do better; and show you understand her imperfections.