By the time we come to the Classical period sonatas have become longer pieces with three or four movements. They would usually start with a fast movement, then a slow one, and then a fast one at the end. If there were four movements the extra one would be a minuet and trio or a scherzo, either before or after the slow movement. The first movement would be in sonata form. The most important composers of sonatas at this time were Haydn, Mozart and Beethoven