"I thought, after they took her, 'She's going to be gone forever. Why?' " the 18-year-old D.C. student said.
But last month Cox found himself in an unlikely position: on the other side of the globe, staring into the majestic animal's eyes again. This time, he was her caretaker.
Cox, a rising senior at McKinley Technology High School in Northeast Washington, had traveled to China through the D.C. Public Schools study abroad program — an 8,000-mile journey that didn't cost him a penny.
The trip was one of 22 offered this summer to DCPS students in the second year of a program that is thought to be the first of its kind for a public school district. Private donations covered the entire cost for more than 400 participants. From airfare to lodging, students paid nothing for the one-week trips, making the program accessible for all regardless of family income.
DCPS officials say their goal is to deepen enthusiasm for learning by exposing students to global experiences.
"Does this lead to students getting higher scores on math exams? No, probably not," said D.C. Schools Chancellor Antwan Wilson. "But that's not what I want to measure."
Wilson said he wants the trips to spur academic initiative, saying that they could inspire "courage" in students to sign up for Advanced Placement courses or further their language studies. Students would then be better positioned for success after high school, he said.
To qualify, students must study a world language at school. Eighth- and 11th-graders are eligible to apply, as well as special education students working toward an alternate diploma.
This year's trips cost about $1.7 million. The D.C. Public Education Fund, which supports DCPS initiatives, provided the funding.
Participants went to destinations in North and South America, Europe, Africa and Asia. Most chose countries where they could practice the languages they have been learning — Spanish students to Argentina, for example, and Mandarin students to China. During the getaways, many also completed volunteer work.
Cox and 16 of his peers traveled the farthest, spending a week at the China Conservation and Research Center for the Giant Panda in Dujiangyan, in Sichuan province. There, they divided their time between caring for the endangered animals and learning about the conservation efforts.
Because travel groups draw from schools across the District, students are able to form bonds across economic and neighborhood boundaries that otherwise might not be possible.
Cox said the trip, from July 14 to 22, pushed him out of his comfort zone. He found it unexpectedly exhilarating.
When the students were presented with a spicy beef-and-pepper dish, he was the first to try it. When locals asked to take the group's photo, he eagerly struck a pose.
That excitement, he said, has changed his outlook on education.
"Before the trip, my future was pretty much, 'I guess I'll go to college,' " Cox said. Now he is certain he will. "This really opened my eyes up," he said. He is especially eager to study abroad in college.
Sarah Elwell, a librarian at McKinley who chaperoned the trip, said that Cox at times had struggled in school. Now she senses he is transformed.
"You give him some freedom and some leadership, and he just runs with it," Elwell said.
Ayanna Morgan, a rising senior at Cardozo Education Campus in Northwest, joined Cox on the trip. Like him, she studied Mandarin for two semesters in her junior year.
Morgan, who turns 17 on Saturday, said she could understand shopkeepers in China but wasn't always comfortable responding. In Mandarin, words with similar pronunciations can have different meanings depending on the speaker's tone.
"I had to watch what I said because I could be calling someone 'a table,' " Morgan said.
Despite her nerves, Morgan said the experience motivated her to continue learning the language, a skill she thinks will help her someday in the job market.
For the teenager, the trip also offered lessons in empathy and appreciation.
Traveling by bus to the panda conservation center, Morgan was struck by the sights outside her window: families, displaced from earthquake-ravaged homes, living in ramshackle tents on the side of the road.
"I don't think school is the only thing that teaches us," Morgan said. "This is another way of learning. It's out of the box, to think about others and to experience someone else's life."
As a condition of participating, students are required to develop projects about their experiences abroad that they present to classmates in the fall. Morgan, who was struck by the prevalence of smoking among young Chinese, is considering a project on health.
Morgan said she is looking forward to answering the most basic of back-to-school questions when school resumes Aug. 21.
"To sit in the classroom and to have someone ask you, 'What did you do this summer?' Well, I went to China," Morgan said.
"Getting to say that is mind-blowing."