On Wednesday, he is expected to announce that within the next 10 years all of the city’s public schools must have a computer science class for all students.

The requirement will face a string of implementation issues. Primarily, there aren’t enough teachers in the field, and there’s no state teacher certification for computer science, according to the New York Times.

Currently, less than 10% of NYC schools offer a computer science course, and only about 1% of students participate in such an offering. The class won’t be a graduation requirement, but it’s a way for students across the income spectrum to try their hand building digital things–and possibly help improve diversity in tech in coming years.

Mayor de Blasio’s requirement follows similar moves by Chicago and San Francisco. The two cities have also committed to requiring computer science programs in public schools.