Possible Clues:

• It's checked by many teachers
• Item to be check in 20-Across
• Push Mother into the middle of syntax
• Functions of words in sentences
• Elementary textbook, to Brits
• Functions and relations of words in sentences
• Study of word and sentences
• Type of school providing Greek in the morning, followed by introductory mathematics and religion
• Rules of syntax
• Live with damage found on Greek language textbook