Former students and teachers at the San Antonio school where he spent two years with Teach for America recalled a conscientious educator, though there are questions about how big his classes were.

In 2011, when a young James Talarico showed up to begin teaching sixth-grade English at Rhodes Middle School in San Antonio, both his new colleagues and some of his students were sure he was in over his head.

Dressed in a pressed white shirt, a blazer and a tie, Mr. Talarico, then 22 and fresh out of the University of Texas at Austin, had never taught before. He was a white man in a school that was heavily Hispanic, dropping in to teach in a lower-income area.

Veteran teachers at Rhodes had low expectations. Like other first-time educators who had come to the school from the nonprofit program Teach for America, they thought, he would be idealistic and eager, and would probably struggle in a room full of sixth graders.

“I thought, ‘My goodness, the kids are going to eat him alive,’” said Tanya Flores, who taught English at Rhodes when Mr. Talarico arrived there.

Instead, Mr. Talarico quickly ingratiated himself with the students and teachers, according to interviews with 10 of them. During his two years teaching, Mr. Talarico developed skills that would serve him on his political campaigns, including his current bid for Senate in one of this year’s highest-profile and most expensive races.

Mr. Talarico’s experience in the classroom has been an important part of his stump speeches during the Senate race and has a prominent place on his campaign website. He has used his time teaching Latino children as an opening to connect with Latino voters, a crucial swing group in Texas, and has sought to use public anger toward a school voucher program put in place by state Republicans to appeal across party lines.

Teaching school has long been a core part of Mr. Talarico’s political identity. He sat on the public education committee in the Texas State House. He helped lead a fight against the creation of the school vouchers program.

And for years, he has spoken about working in overcrowded classrooms with insufficient resources to help pitch for more money for Texas public schools. During the campaign, he has said he had 45 students in his classroom at one point, a number that does not match what appears on official school documents.

“Before I was a politician on stages like this, I was a public-school teacher,” Mr. Talarico said this month during a CNN town-hall event. “I always joke that teaching middle school is the best preparation for politics.”

Mr. Talarico

He decorated his classroom — which he labeled “The Freedom Zone” — with photos of “free thinkers” including Mark Twain, Jay-Z, Dolores Huerta and Julián Castro, then the San Antonio mayor and later a 2020 presidential candidate. The walls were emblazoned with quotations from Frederick Douglass and George Washington Carver.

His assignments included reading the “Hunger Games” series, writing poetry and analyzing song lyrics from Katy Perry and Kanye West. He used the movie “Toy Story” to teach about the emotions of characters and explain plot development.

For his classroom, he maintained an upbeat public Facebook page called “Mr. Talarico” that serves as a two-year diary of his students’ exploits.

Mr. Talarico posted photos and videos of students online, gave out his cellphone number and asked students and parents to call him if they had questions or just to keep in touch. His casual approach to communications and relaxed attitude to the online privacy of his students were a relic of an earlier time on the internet, before schools adopted more controlled methods for how teachers, students and parents interact.

He celebrated test scores that exceeded the district average, documented field trips to colleges and the local minor league baseball stadium, and posted class videos including one about an assignment on media literacy.

“We’re learning about the different elements of TV News stories,” Mr. Talarico wrote in January 2012, “and how to understand news media!”

A Crowded Classroom, but Just How Crowded?

As he talks about the challenges that educators face, Mr. Talarico often says that his student-teacher ratio once reached an alarming level.

“At one point, I had 45 students in one classroom,” he said during the CNN town hall, repeating a story he has told for years. “There weren’t enough desks for all those kids, so I had students sitting on the air-conditioning unit in the wealthiest country in human history — in the 21st century, children sitting on the air-conditioning unit.”

In speeches, Mr. Talarico has frequently repeated the line about 45 students, including in remarks last month to the United States Hispanic Business Council. He also mentions it on his campaign website.

Documents from the Texas Education Agency indicate that the most students ever assigned to a class period that Mr. Talarico taught was 30, with most of his classes ranging in size from 22 to 27 students. In the interviews with Mr. Talarico’s former students and colleagues, they recalled classrooms where every desk was occupied, but not crowding to the point where students were sitting on air-conditioners.

Mr. Talarico’s spokesman, JT Ennis, did not dispute the Texas class size records but said that Mr. Talarico had facilitated a reduction in his class size. He declined a request for an interview with Mr. Talarico.

“After having 45 students placed in his classroom, James worked with school administrators to redistribute students across classes and create the learning environment that his students deserved,” Mr. Ennis said.

Geraldine Uriegas, who taught seventh-grade English in the school when Mr. Talarico was there, said that classes could range in size, with some growing very large. “If you were lucky, you had 30. If you were unlucky, you could have up to 45,” she said. “In some classrooms, students would sit on the old-fashioned heaters.” She did not recall how many students were in Mr. Talarico’s classes.

(More recently, Rhodes Middle School had been under enrolled. The district closed the school this year.)

Critics of Mr. Talarico have also questioned his social media and text communications with students, suggesting that such messages were inappropriate. Mr. Talarico had called attention to some of these interactions himself, such as a back-and-forth with one former student, Brizaida Herrera, over picking a high school in 2013.

Ms. Herrera said in an email to The New York Times that she had no problem with her former teacher. “I have nothing but good memories about Mr Talarico,” she wrote. She added that he had been understanding when she failed to do her homework because “my parents couldn’t pay the electricity bill and so we wouldn’t have any light.”

‘Keep Pushing Yourself’

Mr. Talarico had been assigned to Rhodes Middle School as part of Teach for America, which trains recent college graduates for two-year stints in public schools that are struggling for resources.

He was far younger than the school’s other, more experienced teachers, and was one of just a few teachers who came to school dressed in business attire.

“He was too good for the school,” said Edward Mancha, 25, who was in Mr. Talarico’s English class. “ You could tell that he wasn’t going to be a teacher in a sense that he would be more. I knew he would have no ceiling.”

Though several of the students interviewed said it was clear to them that Mr. Talarico’s ambitions were larger than a sixth-grade classroom in San Antonio, they recalled that he made himself part of the school’s community. He attended concerts and sporting events and opened his classroom after school for students who needed extra help. For those who came, he often had chips and salsa as snacks.

One student, Juan Reyes, recalled being scolded by Mr. Talarico, who warned him not to slack off just because the material was easier for him than his classmates.

“‘I want you to know that you have to keep pushing yourself,’” Mr. Reyes, 27, recalled Mr. Talarico telling him. “He really set me straight in that moment. That lesson really did stick with me.” Mr. Reyes later graduated from Texas A&M University and now works at a biotech company.

A Short Stint, and Onward to Harvard

Miranda Lonazo, who was one of Mr. Talarico’s students and now lives in Denver, said she did not know he was running for the Senate until a New York Times reporter called to ask about her experience in his class.

But, she said, “I always felt like he was going to be more than a teacher.”

“There were kids that really didn’t want to be in the class, but he made sure to make it good for them and to have them be inspired and to want better,” she said. “For sixth grade, that was a lot. He didn’t have to do all of that.”

Fellow teachers also noticed.

Ms. Flores, the former English teacher who conducted observations of Mr. Talarico’s teaching, said that he left his classroom open for students during his lunch time for them to eat.

“That’s something that some teachers don’t want,” she said, because it meant spending their lunch period with students, rather than taking a break.

Mr. Mancha, who now works in the medical billing department for the CVS pharmacy chain, said Mr. Talarico was the first teacher who defended him from bullies at school. Mr. Talarico, he said, ensured that a student who was tormenting him was moved to a different class.

“I felt like he was the only adult growing up in my life who really actually had my back when no one else did,” he said.

By the end of his two-year Teach for America stint, Mr. Talarico had been accepted to graduate school at Harvard, where he would receive a master’s degree in education policy.

On Facebook, he said goodbye to his students and asked them and their parents to keep in touch. More recently, he was again in contact with some of the teachers.

Ms. Uriegas, the seventh-grade English teacher, recalled receiving a Facebook message from him this year. “He asked me if I would donate to his campaign, and I said, ‘Absolutely,’” she said. She gave $25.

(http://www.autoadmit.com/thread.php?thread_id=5915479&forum_id=2#50208962)