That means the person first in line has the same shot at getting a spot as someone who registers on April 1, the deadline. Families will be notified of the outcome by early May.
The move infuriated many, especially those near the front of the line, who said they thought the district unfairly changed the rules midstream and left them with few options for alternatives if their children do not get into Penn Alexander.
Some said they were considering a class-action lawsuit. Others refused to leave their spots on Locust Street near 43d Street, saying they would camp out until allowed to register as planned.
A district official said the parents were free to stay but doing so would not help their chances in the lottery.
"I could understand if they said, 'OK, in the future, we will have a lottery,' " said one grandfather, who said he had traveled for two hours to help his daughter and son-in-law wait in line. "But to do it in the middle of the process, when people have relied on this, that's just unjust. This is a terrible way to treat people."
Like many interviewed, he asked to remain anonymous because he said he feared retribution against his family from the district.
Opened in 2001, Penn Alexander is unique in a district where there are few strong neighborhood schools. It gets $1,300 extra per student from the University of Pennsylvania, which also provides instructional support. When demand for spots became acute, Penn paid to add a fourth kindergarten class in September.
Residents in the area from which Penn Alexander draws pupils pay a premium price for their homes - roughly $100,000 more than they would just a few blocks away - but demand for seats now outstrips the supply. Penn Alexander's prekindergarten registration wait has grown longer in recent years; it used to only be a few hours.
Some applauded the decision. At midafternoon, Terrence McGuckin, who was holding a spot for a friend, a single mother who was scrambling to make child-care arrangements and gather provisions, proclaimed the four-day wait "totally ridiculous. It's totally driven by panic."
The decision was made the day after a Penn Alexander parent raised the issue at a School Reform Commission meeting.
"The way that we do this shouldn't be through who can stand in line the longest," David Lapp, whose child will be in kindergarten in the fall, told the SRC. What about single parents, he said, or people with child-care problems?
Chris Hiester lives across the street from the school and has a child who will be a kindergartner in the fall, but he had vowed not to camp out.
"Part of it is practical," Hiester said. "I have three kids, and it would be a huge effort to be able to pull off having one of us, my wife or myself, be over in that line for four straight days."
But equity was also a concern, he said.
"It's a public school, and if we're still going to have it be a neighborhood school, it should be a lottery," Hiester said. "I think everyone should have the same shot."
Even before the lottery was announced, people were unhappy with the situation. "None of us likes this," said one parent who would not give her name. "None of us wants to be here."
Liza Law was at her desk at Penn's Wharton School, where she is IT director, Friday morning when she heard rumors the line was forming.
She ran out the door, taking the rest of the day off. She had formulated an extensive plan, involving food and phones and tents and child-care handoffs. Trading places in line throughout the weekend would be her parents, who live nearby, her sister and brother-in-law, who live in New York, and her husband.
Law was No. 62 in line, a spot she said might not guarantee her child a place. There were 72 kindergarten spaces this year, but children with special education plans and those in Head Start programs get first dibs.
When the possibility of a lottery was raised, Law said she was unsure she favored the idea. If she was nearer to the front of the line, she would not like losing her guaranteed spot, she said.
But without a guaranteed slot, she said, the lottery seemed like a good idea. "You pay a premium to live in this neighborhood," Law said, "but not everyone can wait in line."
Lynch, the district student-services chief, said the Penn Alexander kindergarten lottery would become a pilot, and in the future, if other schools have more students than seats, a lottery would be used there, too.
As is the case currently, brothers and sisters of current Penn Alexander students will get no special treatment, she said. That also angered some parents with children already enrolled in the school.
Children who do not win spots in the kindergarten lottery will be offered seats in kindergarten classes at schools closest to Penn Alexander, such as Lea School.
Contact Kristen Graham at 215-854-5146, firstname.lastname@example.org or on Twitter @newskag. Read her blog, "Philly School Files," at www.philly.com/schoolfiles.