I saw this on the inside of a classroom and I'm curious as to what kind of flooring this is:
It looks like Terrazzo flooring.
Terrazzo is one of the oldest and most versatile sustainable flooring options. It is defined as a composite material poured in place or precast, consisting of marble chips and/or other aggregates combined within a binder material, which is ground and polished to a beautiful finish. Terrazzo today covers a limitless array of colors, and is known for being durable, sustainable, and flexible enough to accommodate designs from very simple and classic to extremely intricate and complex. From the royal palaces and serene bath houses of ancient times to today’s international airports, hospitals, and schools, terrazzo is a flooring canvas with infinite possibilities.
Of course it has been replicated by vinyl flooring manufacturers and some very old Linoleum was hard to distinguish from the real thing. If you look closely at edges yiu may see evidence that it is a sheet type floor but if no seams can be identified and this is an older commercial building most likely it is Terrazzo
One that hasn't been mentioned, but is common in schools/laboratories, is "epoxy/color-chip" flooring, which is seamless, cast/painted-in-place. A base layer (usually colored), chips of colored plastic scattered, a clear top coat over all. The clear coats may be epoxy or polyurethane, or one of each. The colored chips (need not be colored, but usually are) give some texture to the floor to make it less slippery.