As I recall in my reading of SICP, one of the first big chapters actually hints towards OOP but has you designing it from the ground up. They never call it OOP, but it is heavily leaning towards it; they just happened to set it up using closures (see relevant humorous quotes below). I am referring to the stuff about setting up a virtual function table that switches to the appropriate method based on the type of the data so that multiple developers can write their own way while honoring agreed interfaces/protocols.

"Objects are a poor man's closures." -- Norman Adams (?)

"Closures are a poor man's objects." -- Christian Queinnec (?)