This quote is a caution against excessive use of 'closed' vocabulary sets for writing. These refer to sets that have a limited # of words or symbols, chosen by another person. Limiting students to these sets do not support their growth as writers, as they do not learn to:
• Generate their own ideas
• Translate those ideas using their own words
• Expand their spelling skills
So be sure that students have access to more than closed vocabulary sets. ALL students must have access to the full alphabet!!