There are many different types of families and some students with family situations they may not want to discuss. To avoid all that, I have found it helpful to have class families.
Assign all your students a family role in Spanish. It will help if they follow a predictable pattern. For example, students in the front row are always my children. They next opposite sex student in the row is their spouse. Anyone other students seated in the row are their children. This makes it easy for students to understand who is related to who and how. It also allows for practice of a lot of vocabulary because some students have a class grandmother (me) and grandfather (I typically tell them Enrique Iglesias is their grandfather).
They all have a mother and father. There are also sisters, brothers, cousins, aunts, and uncles.
We then practice some common questions:
Cómo se llama tu hermana? Cuántos hermanos tienes? Cómo es tu abuela? Quién es tu primo favorito?
As we work through the unit, we incorporate the events of the class into our family stories. Someone's dad is absent one day? Someone's son or daughter? I ask them where they are (in Spanish) and we make up a story. I also get extra disciplinary rights as I am now related to them and I threaten to take away allowances. It is a lot of fun and kids will still refer back to their class families and make jokes long after the unit is over. It is a great way to really bond as a class.
Looking for some more ideas for your family unit? Check out these!