Mayor Bill de Blasio kicked off the school year by touting the city’s universal pre-K program, expressing concern about school diversity, and promising to unveil more education policy changes in September.

The mayor’s two press conferences on Wednesday served as celebrations and kickoff events, as city officials marked the second year of de Blasio’s signature pre-kindergarten expansion and the start of a number of ambitious education initiatives. De Blasio also told reporters that fresh ideas were coming soon, saying the city was weighing its options for addressing school diversity and hinting at other announcements that could affect middle and high schools.

At P.S. 9 on the Upper West Side, de Blasio expressed concern about a lack of diversity at many schools across New York, which became a hot topic after a UCLA report last year found that New York City’s schools are among the most racially segregated in the country. However, the mayor stopped short of suggesting policy remedies.

“I believe we have a long history that we’re trying to overcome in this city and in this country of division,” de Blasio said. “We want to be creative. We want to see if there’s other ways we can further this work, because it really is historic and necessary work. But we also don’t have, you know, the perfect solution yet.”

Earlier in the day at P.S. 59, an elementary school in Staten Island, Chancellor Carmen Farina answered a similar question about a recent Chalkbeat story by saying that school diversity comes in many forms, including English language learners and special-education students. The city’s 40 new dual language programs, she said, place children who speak English with those who speak another language, promoting diversity.

She discussed the possibility of working with parents to create “sister schools” and said that there will be more to come from the city on the topic.

De Blasio dropped a few hints of his own, promising announcements aimed at middle schools and increasing college readiness this fall.

As for specifics, “You’ll be hearing more about that in the next couple of weeks,” he said.

De Blasio also visited P.S. 59, where he highlighted New York’s commitment to offering free, full-day, pre-K for every child who wants a spot. So far, 65,504 children are registered for the program.

De Blasio heralded Wednesday’s rollout as “a moment in history.”

“We’ve heard the phrase universal pre-K talked about for a generation,” de Blasio said, “but it was never really true until today.”

He said that his ability to create universal pre-K should work in his favor as he tries to seek mayoral control from the state this year. Last year, de Blasio was granted just one year of mayoral control — which means that he will have to make his case again this coming spring.

“The proof is in the pudding,” he said.