I usually teach the months of the year, not by an unit in itself but by asking ¿Qué día es hoy? at the beginning of my classes and having students practice it with a calendar we have in the room. Sometimes, I incorporate the months into the Weather unit to say something like: “In April the weather is rainy.” (En Abril el tiempo está lluvioso.)
Here is a vocabulary list of the months of the year and the seasons.
Would you like to practice saying dates? Take a look at this packet. It is what a call a Spanish Conversation Bit. An oral practice worksheet you can use with your children/students to get them talking in Spanish. This conversation is all about asking dates!
And here is an extension where students can practice writing dates. They will need the conversation worksheet above as a reference:
You can download it HERE.