One such sign has been erected in the Davenport Road and Lansdowne Avenue area, prompted in part by the situation facing nearby Regal Road Public School, said Maria Rodrigues, the school trustee for the area.
The board has already had to ask a nursery school at Regal Road to move out in order to make space for the rollout of full-day kindergarten there.
"We want parents to be aware that there is a possibility that their children may not be enrolled in the local school and they should do their research before," Rodrigues said in an interview on CBC's Metro Morning.
Meanwhile, 3,200 new condo units are in various stages of approval and development in the High Park area.
Local trustee Irene Atkinson says that will mean 400 new elementary students in her ward over the next few years.
"We have nowhere to put these kids," she said.
Atkinson says several of her schools are already over capacity, and about 270 kids are already being bused to schools in neighbouring wards.
The TDSB is in the process of expanding several schools. But Atkinson says the school board has no say in how the city of Toronto approves condo developments.
"We write back and say, 'Sorry, there is no room in the local schools.' And they go ahead and build," she said.
"So there is absolutely no planning and co-ordination on the part of the city planning [department]."
However Gregg Lintern, Toronto's acting chief planner, says the city works closely with the school board and meets with representatives regularly, including discussions regarding neighbourhood planning studies and a review of the city's official plan.
School boards are notified of development applications at the same time other city departments, he said.
'No easy answers'
But many specifics, such as building size and the number of units, aren't determined until the application process goes through to completion, says High Park Coun. Sarah Doucette.
Moreover, local businesses are keen for additional development and their needs have to be considered, she said.
The city's overcrowded schools are sorely in need of additional capital funding to expand, said Doucette.
"I think we need to go back to the province. I think the province has to come up with more funding."
Both Doucette and Atkinson are trying to come up with creative solutions to the influx of students.
"Can we take over any malls? Can we start building secondary schools in apartment buildings?" said Doucette.
"There's no easy answers, I wish there was."