In my classroom I know there are some students who are far from the Beaver Cleavers of the world. I have several students who have an older sibling that insures they get to school on time. I have other students who are 4th graders who are responsible for insuring their younger siblings get off the bus and together they are latchkey kids. 
I think maybe 3 of my kids come from a family that is the 'nuclear family' model. I have students from single family homes, step-families, and several being raised by grandparents.
This activity made me a little more aware of what it really is like in my classroom.