Speech can be - impulsive, limited to request, limited to rote or scripting. Absence of speech is often times confused as absence of language. That is proven to be an absurd belief by many students who cannot imitate or may have apraxia.
'Purposeful' Speech is not a random speech or an 'end-stop' speech which is a Request speech leading to a Request met. In Purposeful speech, the student participates in learning and understanding of the academic lesson and tries to create a Spelling to Speech system which is meaningful and age appropriate.