One of the language teacher's greatest challenges is finding a way of turning grammar drills and vocabulary practice into something more than rote memorization. Dance makes the perfect teaching medium for a couple of reasons. One: it makes things interesting for students who might not otherwise get a thrill out of memorization. Two: the irresistable rhythm of dance music gets students' bodies involved and makes it easier to side-step the habit of English-to-Spanish translation that so many students are prone to; instead, students connect the concepts of rhythm, movement, tempo and music directly with the appropriate Spanish words.
Before you can teach formal dance you have to know it yourself. Don't fret. You don't have to be an expert, but you should know at least the basic steps and rhythm so that you can pass them on to your students. Have a friend that knows teach you or take a couple of classes from an expert. That's all it should take to learn the basic rhythm. You can even learn online with free basic lessons from sites like www.LearnToDance.com or the Salsa & Merengue Society. Once you're ready to teach your students, keep it simple. Instead of standing in front of them and narrating how the dance will go, show them. Keep the commentary as simple and to-the-point as possible. That way, they have a better chance of understanding, or at least working the meaning out for themselves with the added context of the movement, music and rhythm mixed in. After all, isn't that the point?
Dance can be worked into almost any lesson plan. Don't limit yourself strictly to formal partner dances. Use the Macarena to teach body parts---call them out as you touch them while following the pattern of the dance. Play "Follow the Leader" with students taking turns as leader and having to call out a verb and a body part for the others to mimic. For example: "Move your hands!" would become "Mueven las manos!" and so on. Narrate a line dance for your students, again supplying the words for body parts and movements as the students do them. And if you're feeling especially brave? Take a turn at calling square dance moves out in Spanish.
Going back to formal dances, don't underestimate their power as cultural teachers. Dance is central to culture in some Spanish-speaking countries, and even if your students don't turn into professional dancers, being able to initiate, conduct and then close a dance with a partner will make simple greetings and farewells a whole lot less imposing. When that happens, you know your mission has been accomplished.
For more information on using dance in the Spanish classroom, please see Spanish Vocabulary for Dance.