Hay, a teacher of 20 years, was punched in the face and sprained his ankle as he fell to the ground, chipping the bone.
Principal Garry de Thierry had initially hoped Hay would be back in a week, then later at the start of Term 2, but Hay's continued concussion symptoms have left him unable to return to work.
If you know where Tawhiti-Ormsby is, contact Rotorua police on (07) 348 0099 or the anonymous Crimestoppers line on (0800 555 111). Ring 111 if it's an emergency.