Children are assessed formally and informally, using words, pictures, and toys. Formal assessment involves comparing the child’s skills against the expected norm for their age. This produces a percentile rank that categorizes the child’s ability as mildly, moderately, or severely delayed or disordered. Formal assessment is required for detailed formal reports, such as statementing or tribunal reports.

Informal assessment is carried out for all children at the start of a therapy block. This involves identifying areas of delay or deficit, which are then targeted in therapy. Diagnostic therapy is used to further assess difficulties and test therapy techniques against the child’s engagement and response. Appropriate treatment goals can then be set and therapy tasks can be planned.