To most teachers a class full of open-jawed children means it is time to rethink exactly how to teach fractions. But to Mrs Hendy, a former university drama lecturer and voice teacher, limbering the vocal cavities is vital to improve the way her pupils speak.
She said: "This is not about elocution. I just want children to have the skills to express themselves clearly. It is nothing to do with accent, it is about clarity."
The Qualifications and Curriculum Authority issued guidelines on speaking and listening for primary schools last year and this autumn will send similar guidance to secondary schools.