The city teachers’ union on Tuesday questioned the Philadelphia School District’s ability to safely resume in-person learning this fall, laying out conditions it says must be met before in-person instruction can safely resume for the 2020-21 term.

The Philadelphia Federation of Teachers called for measures from robust contact tracing and COVID-19 testing to stringent cleaning and sanitizing standards.

“There are lots and lots of concerns,” said Jerry Jordan, PFT president. “People are absolutely frightened of the danger that this virus has — it’s unlike anything that we’ve ever had to deal with. My members just keep asking, ‘How are we going to make this happen?’ ”

The union’s plan comes as district administrators prepare to reveal their plans for the 125,000-student district on Wednesday and as school systems around the region and across the country begin to articulate what the 2020-21 school year will look like.

There is wide divergence among already-announced plans, from full face-to-face instruction, which the Ridley School District is aiming for, to 100% virtual, announced this week by Los Angeles Unified School District, the second-largest in the country. Even if they plan to bring students back to class, most districts, including Ridley, are offering a fully remote option for families with health concerns.

Of Pennsylvania’s more than 700 school districts, charter schools, and regional intermediate units, about 100 have submitted fall plans to the Pennsylvania Department of Education. New Jersey school districts must submit plans to the state at least four weeks before classes begin.

The plans coming out now aren’t necessarily final, and are being built with guidance that doesn’t always agree. The Centers for Disease Control and Prevention and other agencies have called for social distancing of six feet inside classrooms; agencies including the World Health Organization and the Bucks County Health Department say three feet is sufficient. President Donald Trump and federal Education Secretary Betsy DeVos have urged schools to reopen fully for the new school term.

“Given the recent national surges and local plateauing of cases, this calls into question the feasibility and safety of a return to in-person learning,” the PFT’s plan said. “As such, the virus mitigation must be carefully monitored and considered in conjunction with funding availability and local, state and national conditions and concerns.”

Meanwhile, city officials on Tuesday announced that all large public gatherings are prohibited through Feb. 28, meaning the cancellation of the Mummers Parade, Broad Street Run, and other city staples. That directive does not pertain to school plans.

Phoenixville’s back-to-school plan includes different options depending on whether the district implements 6-foot or 3-foot social distancing. (At the greater distance, schools could offer in-person instruction on alternating schedules, while the lesser spacing would allow for in-person instruction for all students every day.)

Some districts are continuing to survey parents and preparing to release plans later this month or in early August.

In Delaware County, Ridley is planning to bring all students back five days a week under a plan approved by the school board last week.

”Our number-one priority is resocializing everybody,” said Superintendent Lee Ann Wentzel.

She said the district was aiming to space students six feet apart “to the extent possible”; on Monday, she and staff were setting up elementary school classrooms, using measuring tape while arranging desks and tables.

To achieve six feet of distance, the district is looking at holding some classes in nontraditional spaces. One of the elementary school cafeterias, for instance, could hold 80 students spaced six feet apart, Wentzel said.

”We’re going to be sacrificing some good instructional techniques,” Wentzel said. “How do you teach a kindergarten child to share, when technically, they’re not allowed to share?”

Wentzel isn’t sure how many families will choose Ridley’s fully virtual instruction option.

”It’s one of those chicken-or-the-egg things: It’s hard for parents to make a decision on the plan until they see the plan” — and hard for the district to plan without knowing what families will decide, Wentzel said. She said the district “decided to pull the Band-Aid off” and move forward with its plan.

Still, Ridley must be flexible, she said.

“We fully expect that we’re going to need to make adjustments,” Wentzel said — including in light of what happens in other states where the school year begins earlier.

Cherry Hill School Superintendent Joseph Meloche on Tuesday night released a preliminary plan that calls for a hybrid of in-person instruction two days a week and three days’ remote learning for most of the district’s 11,000 students. The board is expected to vote on the plan later this month.

Parents concerned about the health of their children inside schools may choose remote learning, only, he said. They must commit to that model through Feb. 1. Meloche said ESL and special education self-contained classes will meet in person.

Cherry Hill will continue to provide courtesy busing; the driver and students must wear masks, Meloche said. Parents must check their children’s temperature before sending them to school, he said.

Meloche said some details are still be worked out and urged parents to begin talking with their children about changes to expect when schools reopen and practice wearing masks. Some students will stay in their classrooms and teachers may rotate, he said.

“Education will never look like it did before March 16,” Meloche said.

Elsewhere in South Jersey, the Collingswood School District told parents this week that children will have the opportunity for face-to-face instruction two days a week, with remote instruction for the remaining days. Teachers will have one all-remote day for planning.

“As we settle into the new school year, we will constantly balance safety concerns with student needs and will likely add additional in-person opportunities for students with special needs, those learning English, and those who require additional academic support,” Superintendent Scott Oswald wrote in a letter to parents. “We understand that remote learning worked well for some of our students and not so well for others. We will address each unique situation to the best of our abilities and will move as quickly as possible to provide additional services to students who need them, while maintaining safe, social distancing for all students and staff.”

Collingswood said it would shorten its instructional day “to eliminate the challenges associated with offering lunch and recess. These challenges are simply not manageable in our schools and we believe this is where the greatest risk to students may occur.”

Oswald also prepped parents for further child-care complications: Because of social distancing requirements, Collingswood will not be able to offer enough spots in before- and aftercare programs for those who need them.

Staff writer Melanie Burney contributed to this article.