The campaign against term-term changes in Nottingham's schools will see its first show of parent power today.
A new protest group, Parents Against the Five-Term Year (PA5TY), is staging a demonstration outside the Council House.
The parents are lobbying councillors ahead of a full meeting of the City Council this afternoon. More than 500 have joined a Facebook group, which criticises the proposals to split the school year into five terms of equal length and shorten the summer holiday.
They dispute the council's argument that children suffer from "learning loss" during the six-week summer break.
There are also worries about the impact on families who have children at city and county schools, where the differing term times would cause childcare problems.
Teachers have already staged three one-day strikes over the issue, but have now suspended further action while talks continue.
Nottingham City Council say the changes would improve achievement and attendance and draw on evidence from the USA where pupils have much longer summer holidays.