Students attend therapy sessions in school, or sometimes off site, and while it all falls under the same umbrella, different applications of occupational therapy can look very dissimilar. To improve a student’s handwriting, for example, a therapist might have a child write on a slanted binder, which changes the extension of the wrist. Or, to improve balance and the strength of their core muscles, which allow one to sit up in a chair, children might do the wheelbarrow across the floor as an adult holds onto their feet.

In the hallway of P.S. 503, a little girl named Melissa, with a rainbow of rubber bands in her hair, scooched back and forth on a scooter board, arranging patterned blocks to match an illustration. It looked like a game, but in fact, she was working on strengthening her core and completing multistep activities.

“Does that match?” the occupational therapist asked, holding up the picture when Melissa finished arranging the blocks.

“Of course,” Melissa said.

Thomas Hehir, a professor at the Harvard Graduate School of Education and a former director of the United States Education Department’s Office of Special Education Programs, said that while occupational therapy is indeed a vital service for many children, there may be students on the rolls who do not really need it.

“There certainly are instances where people add services without a strong justification for them,” Mr. Hehir said. While he emphasized that this impulse comes from a good place, a desire to help, the decisions are “often based on the fact that the child has a disability and therefore must need the service, as opposed to this service is needed for this specific reason.”