But this was Sterling's second time traversing the course Wednesday morning. He and his classmates below could talk Williams through it.
"Casey, don't bend your elbow," one bellowed from the ground. "Make sure you stand up straight," another said.
Both made it.
Bok is one of 23 Philadelphia schools closed by the School District this summer to help resolve a budget shortfall. Next month, enemies and rivals will become classmates and teammates when Bok students migrate to Southern, a school that has in recent years been plagued by racially motivated violence.
To smooth tensions, the district hired Outward Bound, the outdoor-adventure group, to teach student leaders from the schools about teamwork, leadership, and diversity. The hope is that if the student-government leaders, athletes, and honor society presidents respect one another, the student bodies will follow.
Over the last six weeks, Outward Bound has worked with students from Bok and Southern and has run a larger program for students from Germantown and Martin Luther King High Schools. Fifteen students from Bok and Southern have participated in the activities, which were held three times a week and end Friday.
Katie Pastuszek, executive director of Outward Bound in Philadelphia, said the racially diverse group of students was chosen by school leadership. Half the students in Wednesday's session were black, and the other half were Asian or white.
"We believe there is no greater way to form a tight-knit family, if you will, than to bring a group of individuals together," Pastuszek said, "and offer them a challenge and adventure that they go through together."
Last year, 57 percent of students at South Philadelphia High were African American and 28 percent were Asian. The student population of the new school is expected to have more African American students than before.
During the 2009-10 school year, Asian immigrant students were repeatedly attacked by African American classmates at South Philadelphia High.
At the park, students from the schools said that while they had preconceptions about students from the other school, the last six weeks helped dispel those stereotypes.
"We were hearing bad things about Bok students, so it was kind of a relief when we were all united," said Steph Abedejos, 17, a rising senior at South Philadelphia who is Asian. She had not known anyone from Bok before the program and had heard chatter that Bok students could act violently.
Williams, a black student from Bok, had not known anyone from South Philadelphia High. He was primarily worried, he said, about how unfamiliarity among students would affect the football team's performance.
He understands that this fall, he'll have to see himself as a South Philadelphia Ram.
"We're going to be one school. Everybody needs to get along," Abedejos said. "We can't be two schools in one school."
Contact Theodore Schleifer at 215-854-5607 or firstname.lastname@example.org, or follow on Twitter @teddyschleifer.