A school appealed directly to parents to help recruit a new geography teacher due to supply staff shortages.
Colchester County High School for Girls managed to fill the role, but experts say there is a widespread teacher shortage across Essex.
Grainne Hallahan, of educational publication TES, said coastal and deprived areas in Essex were particularly hard to recruit for.
The TES website currently lists 132 teaching vacancies across Essex.
The figure is the highest for any county in the East of England.
Last week numerous to cover.
The latest data shows 8.6% of teachers and school leaders were absent on 6 January - and 4.9% were absent because of Covid, up from 3% on 16 December.
An email to parents at Colchester County High School for Girls said the impact of Covid meant supply cover was needed in the geography department and asked them to ask "anyone with the relevant skills and experience to get in touch with the school."
Simone Payne, chief executive of 4myschools, a teacher recruitment agency in Chelmsford said it had had more requests for its services year-on-year.
Teachers were looking for "greater flexibility", leading many to leave full-time work and sign on with agencies, she said.
"It doesn't surprise me they filled it by putting out to parents because a lot of the teachers on our books are parents," she said.
Long-term supply work was becoming more common with teachers fulfilling the same role as permanent staff by getting to know pupils but feeling more able to call in sick if needed, she said.
"They have flexibility that if something kicks off in their personal life they can say they can't come in. So I think that flexibility is key and it's not just in the education sector," said Ms Payne.
Key subjects like English, Maths and Science were facing the greatest shortages, Ms Payne said.
TES analyst Grainne Hallahan said: "Essex has some unusual and individual geographical trends when it comes to teacher recruitment. You're very close to London but we also have lots of coastal schools... it makes it really challenging for teacher recruitment.
"So we know have particular pockets in Essex where it is particularly challenging to recruit teachers and these problems aren't going away."
She agreed that teachers need "more flexibility" to encourage retention in full time roles.
Find 365Nainanews News: East of England on , and . If you have a story suggestion email email@example.com