Possible Clues:

• Sounds like it was hard to give lessons in the past
• Worked in school, audibly showing strain
• Said to be stressed as a pupil
• Shown how to make this tight, by the sound of it
• Educated abstainer concealing a disgusted expression
• How scholars are reported to be stretched
• Reportedly tense on being instructed
• Stretched, say, getting conditioned
• Was a teacher reported as tense?
• Disciplined for making wrong sound