Thing One picked the theme "Tchaikovsky", and momma expanded it a bit to cover classical music in general. We are learning about orchestral instruments and a bit about the science of sound.
We found a neat book at the library. It's a great survey of classical music in general. It covers each era, then each instrument in the orchestra. The accompanying CD has nice, short, well-chosen samples for each era and each instrument. It's called The Story of the Orchestra by Robert Levine.
We listened to tons of music of course. Our favorite fun cds are Beethoven's Wig I and II. I found some great online lessons at the Baltimore Symphony Orchestra's website.
Here are some other neat online music links.
We practiced clapping rhythm along with simple songs. It's also fun to make up verses to songs like Old MacDonald had a Farm, and Down by the Bay. We also found the echo spot in our stairwell.