Kids are 4 and 5 years. I showed documents related to our previous studies(spouse and myself), Our bank statements (in each of our names and together), resumes, job letters of myself and spouse, marriage certificate, acceptance letter from the University. Just the basic stuff they asked for online. Must tell you that I did an SOP too. Most applicants from this side of the world seem not to include one, as our application was paper based, we used it to say why we wanted to go as a family. I am not sure if it made a difference, but it doesn't hurt.