Re: Is a public school conjoined to a city park not in session considered a public place where one can film?

The answer to your question is: NO!

Public Schools not-in-use are not public spaces. You cannot legally jump any fences or walk through any gates at any time without permission from the school principal.

You cannot (legally) aim your camera at the public school not-in-use without permission from the school principal.

You cannot (legally) screen your footage of the public school not-in-use without permission from the school principal.

Custodial Care laws are what give the principal a lot of power over the school's health, safety, and welfare.

Long story short: Call the principal and ask for permission.