Ms Ellis, who goes by the name of Penny on the voyeuristic gameshow, faces losing her job after her towel slipped as millions of Internet and E4 viewers watched her coming out of the shower.
Cauthar Tooley, head of Sarah Bonnell School, a girls' comprehensive in Stratford, east London, where Ms Ellis teaches English, warned she would sack the 33-year-old if the school's reputation was tarnished.
Meanwhile, in a chat with housemate Stuart, the teacher suggested her days in the classroom are numbered. She said: "It would be lunatic (to return). I wouldn't get any work done. It's best not to go back for the safety of the kids and the structure of the school.
"It would be a dream come true if the Royal Shakespeare Company called up and said 'We'd like you for our next producation'."
Pupils and some parents at the school refused to condemn the self-confessed "eccentric". Penny Finch, 16, said Ms Ellis was one of the school's best teachers and "more of a friend than a teacher".
Rita Rodger, whose 13-year-old daughter attends the school, said she did not have a problem with Ms Ellis returning, but some parents were bound to make a fuss.
"It's just a laugh, but it depends what she does. She's a role model for the girls." <> Ms Tooley praised Ms Ellis's dedication, adding: "She is a bit wacky but that's what makes her a good English teacher."
The head will meet with governors and Newham LEA solicitors to discuss whether Ms Ellis's behaviour has infringed the school's code of conduct when she leaves the house.
Tim Harrison, regional secretary of the National Union of Teachers, said the school should not take action against Ms Ellis, a union member, who had been given permission to take part in the show.
Ms Ellis has been shown kissing housemate Paul, 25, and massaging male and female contestants.
Despite being a born-again Christian she even joked that she would have sex in the house to help her win the pound;70,000 prize. Bookmakers gave her a three-to-one chance of being nominated for eviction today, as the other house-mates feel she is too bossy.
David Buckingham, director of the Centre for the Study of Children, Youth and Media at the Institute of Education, said it was difficult to predict how her students would respond to her gameshow performance.
"It could enhance her status as the epitome of cool, but it could completely undermine her authority in the classroom," he said.
Should she be sacked? Have your say www.tes.co.uk
Big Brother is on Channel 4 six nights a week with live feeds on the digital channel E4 and www.channel4.combigbrother