The academic results are early, and at 240, the sample size of students is small, but the inaugural classes of third and fourth graders at I Promise posted extraordinary results in their first set of district assessments. Ninety percent met or exceeded individual growth goals in reading and math, outpacing their peers across the district.

“These kids are doing an unbelievable job, better than we all expected,” Mr. James said in a telephone interview hours before a game in Los Angeles for the Lakers. “When we first started, people knew I was opening a school for kids. Now people are going to really understand the lack of education they had before they came to our school. People are going to finally understand what goes on behind our doors.”

Unlike other schools connected to celebrities, I Promise is not a charter school run by a private operator but a public school operated by the district. Its population is 60 percent black, 15 percent English-language learners and 29 percent special education students. Three-quarters of its families meet the low-income threshold to receive help from the Ohio Department of Job and Family Services.

The school’s $2 million budget is funded by the district, roughly the same amount per pupil that it spends in other schools. But Mr. James’s foundation has provided about $600,000 in financial support for additional teaching staff to help reduce class sizes, and an additional hour of after-school programming and tutors.

The school is unusual in the resources and attention it devotes to parents, which educators consider a key to its success. Mr. James’s foundation covers the cost of all expenses in the school’s family resource center, which provides parents with G.E.D. preparation, work advice, health and legal services, and even a quarterly barbershop.