The Fun Music Company has a whole series of lesson plans available about composers, from the Baroque through to the 20th Century.
Here is a great listening activity for Music by Mozart:
Before beginning this activity with the class, write a selection of emotions/moods on individual small pieces of paper (e.g. frightened, perplexed, rolling on the floor with laughter, chilled out, just been stung by a bee etc.) You could even come up with these as a class. Now choose a short phrase such as “I think it might rain”. Choose students to come out and randomly pick one of those pieces of paper.
They must then say that phrase in the mood or emotion that their paper suggests, using changes of pitch, body language and speed of speech to best represent it. The class tries to guess which emotion the chosen student was acting out. Try as many of these as possible.
Now discuss how a single melody can be altered to give a variety of effects. Music that does this is called a set of “Variations”.
Listen to a very short excerpt from the very beginning of Mozart’s 12 Variations and identify what we know this song as today (Twinkle, Twinkle Little Star). Have the students write up a chart, or do it as a class listing the different variations and their similarities.
Piano Concerto no. 21 2nd movement: Andante