Schools and colleges are pretty decent, depending on location, neighborhoods, etc. Public schools are a bit all over the place where it regards quality, but all around Lisbon you have a lot of private schools (German, French, US-inspired, etc.). Best colleges tend to be public, though.
They are relatively big buildings. Kids go there and receive lessons in different subjects( stuff like Math, History, Geography, etc) from dedicated personal(known as teachers), it is OK I guess. The bad thing is that there is no pledge of allegiance ceremony, you cannot pick your curriculum and you HAVE to vaccinate your kids, but not everything can be good.