Forum:The Hogwarts Classes...

I don't know if it even specifies in the series, but it seems none of the articles pertaining to Hogwarts or the subjects taught there tell which Houses have classes with which. Are there two Houses having class together in every subject, or only a certain few? I know that Gryffindors have had Herbology with Hufflepuffs, Gryffindors have had Flying Lessons with Slytherins, and Ravenclaw has had Divination with Gryffindors. Are those the only classes where more than one House have class together, aside from N.E.W.T. level?