One of the biggest tragedies of public education these days is the continual reduction, if not outright elimination of, the arts. Suits and Skirts decide students need more math and science and in the interest of time and money take away music and recess, the very things that would help students better understand math and science.
Psychology Today, in an article entitled
"Einstein on Creative Thinking: Music and the Intuitive Art of Scientific Imagination" writes:
"For Einstein, insight did not come from logic or mathematics. It came, as it does for artists, from intuition and inspiration. As he told one friend, 'When I examine myself and my methods of thought, I come close to the conclusion that the gift of imagination has meant more to me than any talent for absorbing absolute knowledge.' Elaborating, he added, 'All great achievements of science must start from intuitive knowledge. I believe in intuition and inspiration.... At times I feel certain I am right while not knowing the reason.' Thus, his famous statement that, for creative work in science, 'Imagination is more important than knowledge' (Calaprice, 2000, 22, 287, 10)."
In addition to being an amazing physicist, Einstein was also a violinist and pianist. It is well documented that in addition to just enjoying the heck out of music, he relied on it to help him think. Whenever he got stuck on something, he played music until the solution revealed itself.
I could go on and on about the merits of music and the arts, but this post is about resources and ideas for music in units.
Of course, you can straight up do a music unit study. You can do a unit on a specific composer, or on a musical period such as Baroque, Classical, Romantic. You can do a comprehensive unit on the history of music, or the instruments of music, or a smaller unit on a musical genre like Jazz. There are so many publishers of ready-made music units, and great books on instruments and composers, etc., that it would take all day to point them out. One lesser known, but fabulous supplement to music unit studies is Patrick Kavanaugh's
Spiritual Lives of the Great Composers.

In addition to materials by big publishers Dover, Bellerophon, Usborne, Teacher Created Materials, etc., there are single teachers creating and sharing or selling helpful materials or lesson plans. Deb Chitwood at Living Montessori Now has put together a ton of
Montessori-Inspired Music Unit Studies.
Julia Jooya has created many tools and mini music units. Her (free) unit on
Blues Music can be both a unit in itself, or a portion of the music part of an American history unit that covers some history, language arts, and music instruction. It isn't hard to find unit study helps ON music.
What can get tricky is finding ways to incorporate music into unit studies of other topics, especially if they're science topics. Examples like Tom Lehrer's
"The Elements Song" and James Fodor's
"Periodic Table Song" and
"The Atoms Family" song, sung to the tune of "The Addams Family," demonstrate the possibilities. (As these three songs all use the tune from other more familiar songs, you and your children could take cue and try to write your own catchy science songs in the same way.) I love the science songs and videos from They Might Be Giants like
"The Bloodmobile." (You can
order CDs and DVDs of these as well, including ABC and 123 albums.)
As my children's piano teacher, I've taken advantage of being free to kill two birds, so to speak. I like to use piano music to enhance geography and social studies with music books like:
There are musical memorization tools, also, like Audio Memory's
States and Capitals Songs, which gave my children a HUGE edge in a geography bee several years ago. (My then three-year-old had more state capitals memorized than the rest of the participants two and three times her age because we listened to this on car rides.)
From "Wee Sing America" to "Wee Sing Around the World" to "Wee Sing Halloween," my young children and I have always appreciated
Wee Sing CDs. They have been staples in some of our units.
I've shared several resources here, but really they're just the tip of the iceberg. With the ease of an internet search, it isn't hard to find some way to include music into each and every unit. So make sure you do!