An easy way is to use Advanced Find that adds Accounts or Contacts that have received quotes for a Class:
* Setup the Workflow and Marketing List (below) for classes
* Open Advanced Find and select the type to add (Account? Contact?)
* Click select and add Quote (Potential Customer)
* Select name contains
* Save the Advanced Find as CRM 101 Quotes
When you want to populate the CRM 101 Marketing List, open the Marketing List and click Manage Members. Use Advanced to Add Members and select the saved Advanced Find named CRM 101 Quotes.
This will give you a list of interested students and provide a means to communicate with them.