Why does BECOME ask for student DOB with the class roster?

We request date of birth only as a way to verify student account ownership, especially for when students change schools. Since names can be common and emails can change in the new school, the DOB information helps identify that student in our system.  In the BECOME database, on the Microsoft Azure cloud hosted in your region's data centre, all dates are stored as a high resolution epoch value that looks like "633524544000000000". This is not easy to read or convert and sits behind multiple layers of Microsoft security. The Class Rosters spreadsheet is destroyed after student logins have been created.