When Chutong Tan, 21, came to the United States from China four years ago, she spoke just a few words of English. After her first day at Solomon Charter School in Chinatown, she was in tears, said her stepfather, Allan Wong.

Solomon offered no formal language support. Tan soon transferred to Furness High School in South Philadelphia, and things began to turn around.

At Furness, where nearly half of the students are English language learners (ELLs), Tan said, she felt much more comfortable.

After four years of high school, Tan was admitted to La Salle University for the fall. But she still worries that her English proficiency is not up to par, and wishes the language program at Furness had been more intensive.

"I am panicked," she said. "I feel like I cannot catch up."

Students such as Tan who begin learning English in their teens face compounding obstacles - they are given more complex material and less time to absorb it, said Allison Still, deputy chief of Multilingual Curriculum and Programs for the Philadelphia School District.

"The language demands for students in high school are much higher than language demands in elementary school, or even middle school," Still said. "So that gap between a student's language proficiency and the language they need to really access the content is much bigger."

Wong said his stepdaughter is one of the lucky ones - she was able to transfer to a school with a developed ELL program, and unlike many of her new-immigrant classmates, she had a parent fluent in English supporting and tutoring her.

Last month, the Philadelphia Education Research Consortium released preliminary findings on English language learners in both district and charter schools in Philadelphia. The research noted the long-standing achievement gaps between ELL students and native speakers - as well as the growing and increasingly diverse nature of the ELL population in the city.

Wong has become an activist, urging the district to expand its English-learner offerings, particularly at the higher grade levels. Beyond reading and understanding English, he said, students need to become comfortable with writing and communicating.

"As she has improved her English, other subjects have improved, as well," he said of Tan. "Language has been the main barrier."

Still said the district needs to improve collaboration between ELL teachers and teachers of such grade-level subjects as math, science, and social studies. Students' language ability, she said, should not prevent them from accessing those other academic areas.

Rosemary Hughes, director of the Philadelphia Education Research Consortium and one of the authors of the ongoing study, echoed Still's observations.

"At the early, early elementary level, a lot of what's happening in the grade-level classrooms is focused on language development and literacy development," she said. But in high school, students should be spending more time with grade-level content.

The consortium's research showed educators complaining of a lack of ELL-specific resources across city schools, and a lack of training for teachers on how to best work with ELL students.

Looking back at high school, Tan said she would have liked more feedback and individual attention from language teachers, and more support in other classes such as math and science - subjects she enjoyed but often had trouble in because of language difficulties.

In 10th-grade biology, for example, she barely understood the lessons in class and relied instead on an Internet translator to get through the textbook at home.

Tan said she would have liked to study psychology and perhaps become a therapist. But she worries that her hesitation in speaking English would make that too difficult.

Instead, she plans to study nutrition at La Salle.

Still said certain ELL improvements have taken a backseat to a broader shortage of resources in the district: fewer teachers, less planning time, and limited professional development.

"Having that limited flexibility for the content teacher and the ESL [English as a second language] teacher to collaborate, share the units that they're working on, share the student data that they're collecting - that has really had a big impact."

Wong acknowledged these challenges but said he will continue pushing the district to pay more attention to the issue.

"If my child is having this problem, I can see other new immigrants having it, too," he said. "I'm the exception, so it's my responsibility to do something."