PHILADELPHIA (CBS) — Philadelphia teachers continue to protest the return to in-school learning. On Friday, they gathered near the home of Mayor Jim Kenney.

Roses are red, violets are blue, some Philadelphia teachers are angry at you know who.

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“We’re here for a ventilation valentine for Mayor Kenney,” high school teacher Max Rosen-Long said.

Delivering box fans — a reference to the school district’s plan to ventilate school buildings with the simple devices — a few dozen teachers lined the Old City street near the mayor’s apartment, making it known they are not too happy with the safety conditions at schools.

“My own partner is at risk when I’m going to spend the whole day worrying about her and her safety as well as the safety of her and her kids, and her school and her parents and families,” Rosen-Long said.

This protest comes days after the Philadelphia Federation of Teachers union instructed its members not to return to school as planned this past Monday, to prep their classrooms for the return of Pre-k through second graders scheduled for Monday, Feb. 22.

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“I am willing to keep working hard and keep carrying materials that I need so we can wait until the buildings have the appropriate ventilation and keep the appropriate measures to keep us safe,” kindergarten teacher Christina Gutierrez said.

Friday’s protest comes the same day the CDC urged states to reopen all K12 schools under new guidelines, using four color-coded zones to determine the level at which the school could reopen.

A spokesperson for the Philadelphia School District applauded the updated guidelines in a statement adding, “We look forward to welcoming our first phase of pre-k through second-grade students for in-person learning on Feb. 22. To date, our school district has incurred over $65 million in COVID-related expenses.”

Jerry Jordan, the president of the Philadelphia Federation of Teachers, writes, “We’re encouraged by the new guidance because it recognizes the need for a multilayered approach to mitigation. We’re not going to speculate right now on when district schools will be safe for re-occupancy.”

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On Monday, the Our City Our Schools coalition will host a virtual rally calling for the city to ensure vaccinations are widely available, and all school buildings are properly ventilated before reopening the classrooms to faculty and students.