How can you rate a child's level of frusation and determine if it's normal?

Question by Holly: How can you rate a child's level of frusation and determine if it's normal?
8yo seems to become overly stressed and frustrated with many things. She reats physically - wringing her hands, stretching her body (legs), and the odd time hitting her forehead. Docs have said she's fine - but I want to help her. The type of things she gets frustrated with are having to brush her teeth, do homework, make bed. Also she gets frustrated when children don't understand her ideas

depression and anxiety scale