But his public school teacher spotted his unusual work ethic and "through a blessing and good luck" introduced him to a private school in East Palo Alto, where he could live in a dorm and get round-the-clock support.
Thornton today is a Stanford University freshman, working at the tech help desk in the undergraduate library, singing in the Black Men's Chorus a cappella group and preparing to declare a major in computer science.
Though he always aspired to attend college and his father supported the dream, Thornton says without the extraordinary preparation he got in his six years as a student at Eastside College Preparatory School, things might have turned out very differently.
"It definitely wouldn't have been the same — I would have been on my own in the whole process," he said.
Now in its 18th year, Eastside Prep is a one-of-a-kind institution, combining rigorous academics, an uncommon level of teacher and volunteer support and sustained investment of donors from the other side of the freeway toward a razor-sharp mission: getting first-generation college students to succeed in four-year colleges and beyond.
"We believe every student who becomes the first member of his or her family to go to college has a profound impact not just on that student but on the whole family," says Principal and co-founder Chris Bischof.
Starting with that conviction and little else, Bischof and Eastside co-founder and Vice-Principal Helen Kim — friends from their Stanford undergraduate days in the early 1990s — have built this unusual school from scratch, learning and adapting along the way.
The two teachers had eight students when they launched their startup in 1996 at a park picnic table in East Palo Alto, later moving to borrowed office space and eventually to a few portable classrooms on a donated 1.6-acre parcel on Myrtle Street.
From the picnic-table beginnings, Bischof over the years has corralled donor support to build state-of-the-art classrooms, a computer lab, a theater, a gym, a cafeteria and even a dorm — all surrounding an open, grassy quad.
Enrollment has grown to 300 from the original eight, with every one of Eastside's 388 alumni so far accepted by a four-year college.
Eighty-two percent of Eastside students come from East Palo Alto or eastern Menlo Park, though some of those are among the one-third of Eastside students who live in the dorm because of the extra structure and support offered there. Bischof himself has resided on campus for nearly the entire history of the school.
It may be only slightly accidental that many amenities available to Eastside students — hot meals, tutorials, dorm-room inspections — resemble those at the New England boarding school where Bischof spent his own high school years, Phillips Academy in Andover, Mass.
"There are some common elements, and differences as well," said Bischof when asked about the comparison.
"We've tried to create a school that has high expectations and is really rigorously going to prepare our students for college across the board. Having been in those environments, it helps to know what those expectations are like. And we hope that with the same expectations and the right type of support, our students can be equally successful."
Vice-principal Kim oversees Eastside's faculty and curriculum, including unique features like "Friday Night Homework" and an intensive middle-school reading program.
Receiving no public funds, Eastside is free from the strings and bureaucracy that accompany them, allowing it wide berth to customize teaching to student needs.
The flip side is that Bischof must constantly fundraise — to the tune of $17,000 per student per year — to keep the operation afloat, a task he calls "a huge struggle, and a real challenge from year to year."
Parents, most of whom are low-income, are asked to pay $250 a year — plus an extra $100 if their child lives in the dorm — and contribute 20 volunteer hours.
With 55 staff members (38 full-time-equivalents), the school's operating budget is $6.4 million, covering the year-round program, the residential program and the alumni support. It costs $10,000 to house a child in the dorm. Ninety percent of Eastside's support comes from individuals, with the balance from foundations and corporations.
In the case of Joseph Thornton and many others who've gone through the school, financial support came from donors who agreed to sponsor an individual student.
While many of his classmates wrote their thank-you letters to anonymous sponsors, Thornton said he felt lucky that his sponsors — a San Francisco couple with a young daughter who took him on as a seventh-grader — wanted to get to know him personally.
They met for lunches and visits and, the following year, invited Thornton to an event at their home to speak about his Eastside experiences with prospective donors to the school.
"It went well actually," he said. "I had a lot of fun, met a lot of people, and did more of it. It's a great experience because you learn how to interact with people of different backgrounds, understand their experiences and understand the whole experience of networking."
The San Francisco family kept on sponsoring him every year through high school, Thornton said, and the relationship continues today.
As word about Eastside has spread, admission inevitably has grown more selective.
First and foremost, says Bischof, the school is looking for first-generation college-bound students from low-income families. "Within that subset, we're looking for students who want to be here."
Students must commit to an 8 a.m. to 5 p.m. school day — plus homework — and an academic calendar that runs year-round, including summer school or other summer activities deemed worthy. Bischof personally interviews every applicant.
"They're really looking for that spark in kids," said John Jacobs, a retired public school teacher now in his seventh year of volunteering at Eastside.
"Not necessarily the smartest ones, but kids they feel they can keep on a college track. They have a lot of kids — maybe even a majority of sixth-graders — who are not working at grade level when they come in."
Academics at Eastside combine rigor with an elaborate support structure.
"There are no shortcuts," Spanish teacher Shaneka Julian said.
But "confidence-building — defining students as intellectuals and scholars — is a huge part of the culture," said Marianne Chowning-Dray, who taught calculus at Gunn High School for nine years before joining the Eastside faculty in 2005.
"It's assumed that everyone will participate, everyone can do this, that all students can achieve at a high level. We don't take no for an answer," Chowning-Dray said.
That culture felt strange to Thornton when he first arrived as a student. "Normally students fear seeking help or talking to the teacher because they don't want to seem stupid or dumb for asking questions or not knowing something, but at Eastside we expected ourselves to ask these questions, we expected to meet the teacher outside of the class.
"They give you their email address; they give you their number. They do like sleeping, so they prefer that you contact them earlier, but if you contact them even at 10 p.m. and they're still awake they'll definitely help you out."
Eastside relies on volunteers to staff an intensive middle-school reading program, in which students begin their day with an hour and a half of intensive reading and writing.
Volunteers like John Jacobs make it possible to break the students into small groups of four. "Each morning we read a chapter out loud," Jacobs explained. "We monitor the reading, we do vocabulary and comprehensive exercises and the kids do a writing response every day."
Vice-Principal Kim oversees "Friday Night Homework," a routine that helps ensure no assignment is left undone. Students with incomplete work in any give week are required to stay on campus Friday evening until it is finished.
Since Eastside's early days, Kim has tracked which students are missing which assignments. Now it can be done by computer.
"Friday afternoons we run a report of all missing assignments of all students," she explained. "I do a lot of rounding up and calling parents to tell them not to pick up their student at 5 because they have to stay and complete assignments."
She considers the Friday night routine a "safety net" for kids who otherwise may consider the incomplete assignments "out of sight, out of mind."
"Here, the work doesn't disappear, and if they've turned in all their assignments they're much less likely to do poorly in a class," she said.
Chowning-Dray, the math teacher, made the switch from Gunn to the Eastside faculty after becoming familiar with the school through helping, as a volunteer, to establish its calculus program.
"We built the program for AB calculus, and then they decided to expand to a BC sequence," she recalled, referring to the more advanced course. "At that time I thought that would be a great match for me. It was an opportunity to reapply my skills and the knowledge I'd amassed over the years and put it toward this great mission."
Content-wise, teaching math at Eastside is similar to teaching math at Gunn, but the culture of Eastside sets it apart, Chowning-Dray said.
"What might be assumed at another school we're very intentional about here," she said. "If a student isn't doing their homework or outside assignments we notice that and try to figure out what's going on and get that student back on track.
"Students can fall through the cracks in a lot of schools, but I'd say Eastside is sealed really tight.
"I think a lot of efforts are being made in public high schools to create that sort of environment, but it's tough. What works here isn't necessarily scalable, but parts of it are. It's a lot about the people — the longevity of the leaders, the vision of the people who work here."
Chowning-Dray has a total of about 100 students in her section of BC calculus and three sections of algebra II-trigonometry, as well as an afternoon study hall. At Gunn she might have had five classes with 30 students each.
But while they may have fewer students to keep track of, Eastside teachers and staff wear many hats.
Shaneka Julian, who teaches first-, second- and third-year Spanish to non-native speakers, also advises Eastside's Engineering Club, coaches the girls JV basketball team and fills in as a substitute dorm adviser. Bischof coaches boys basketball.
One of many lessons Bischof and Kim have learned is that, for first-generation students, college admission is only the start of the journey.
"At the beginning I was very naive and just thought if we could get them to college it would be a ticket to a better life and the rest would take care of itself," Bischof said. "But we learned that first-generation college students face challenges that most of us who went to college can't even imagine.
"We saw some students able to be successful but others who did struggle, especially in that first year making the transition from the highly supportive environment here to a larger institution where they really were pioneers in their family and it was very easy to opt out if they didn't get off to a good start. That was eye-opening to us," Bischof said.
These days Eastside grads who are college freshmen, such as Thornton, get weekly or biweeky emails and calls from the school.
"They visit all the freshmen on their campuses," Thornton said. "And they call you and ask 'How's everything going? What's new? Are your classes too demanding? Is everything fine at the dorm? Is anything surprising you?'"
Freshmen and sophomores are a particular focus, says Eastside's Alumni Program Director April Alvarez.
"Those first two years in college are crucial, and once they make it past that they're very likely to finish," she said.
Eastside staffers such as Kate Hiester also work year-round to help grads find summer internships and job leads — much like a well-connected parent would.
Another post-graduate "stabilizing force" for Eastside alums is the fact that most enter college with some academic credit already under their belts.
Longtime English teacher Amy Reilly recently went through the hiring process at Foothill College and now offers Eastside seniors a year of college-credit English.
The class, recognized by most UC campuses and all California State University campuses, is taught at Eastside but runs on Foothill's calendar. It adheres to Foothill guidelines, which include a 750-word minimum on assessed papers and a requirement that students generate at least 6,000 words per term. The first semester draws on nonfiction to cover different modes of writing — observational, autobiographical, position papers, speculation about cause and effect and evaluation. The second semester is fiction-based, with students reading and analyzing "Crime and Punishment," "In Cold Blood," "Oedipus Rex" and "Antigone."
"Our students are very well prepared in the humanities and this gives them even more confidence, and also room — if they make a mistake at the beginning — not have their financial aid frozen after a quarter or two," Reilly said.
All Eastside seniors also are required to produce a 25-page research paper using peer-reviewed literature and make a 30-minute presentation on the topic.
After three decades of public school teaching — mostly middle-school math in a tough, East Bay district — longtime Eastside volunteer Jacobs is in a position to make comparisons.
"I was in a school full of tough kids. We had a good staff, good administration, but we were always plugging up holes in the dike. We couldn't do it fast enough — you always felt you were a couple of steps behind.
"You have a lot of kids in the school ready to jump at a quality education, but it's very hard to provide it at the level we want to. Ten percent of the kids take up a lot of everybody's time, and you never have enough people."
The small scale of Eastside mitigates many of those factors, Jacobs said.
Cofounders Bischof and Kim seem to be universally revered on campus.
At Eastside, Jacobs said, "Kids can't walk across campus without several people saying hello and meaning it. Chris and Helen will stop and talk to them about whatever, make a connection.
"And they don't sit still. They're always pushing the envelope, trying to level the playing field."
Parent Mimi Pearson said, "Any time Chris or Helen ask me to do anything I'm dropping everything to do it. They gave my daughters a chance, and they didn't have to. I'm never taking that for granted."
At this point the cofounders have no plans to expand or try to replicate their school but, having graduated 14 classes, are starting to see some of the long-term impact of their enterprise coming into focus.
"We can see (graduates) advancing in their careers in the short time they've been out of college," Bischof said. "They serve as role models and stay closely connected to the school."
Some have remained in their college communities or moved away for professional opportunities but, he said, a majority return to the area, with many working in education. Some are teaching in East Palo Alto's Ravenswood City School District, and one even moved into the dorm along with his wife to take on the job of resident fellows.
"The feedback from our alumni really informs what we do at the high school level," he said. "We'd be the first to say that this is a work in progress, and we continue to learn."
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