VB6 / Visual Studio 6 exist. That is true. But these versions are really old and at that time no express versions was available.
I do not know of a freely available download of vb6 (But at the moment I do not see any reason why such an old version should be used ... But I am quite sure that there was good reasons to use that in your programming class.)
But be aware: VB6 is not VB 2006 or so ... versions was:
6 (without .Net)
2002 (.Net 1.0)
2003 (.Net 1.1)
2005 (.Net 2 and previous)
2008 (.Net 3 and previous)
2010 (.Net 4 and previous)
2012 (.Net 4.5 and previous)
With kind regards,
Konrad