I have added a section on practice in proving theorems to my
public domain materials website. Here is the exact location of
it:

www.public-domain-materials.com/practice-proving-theorems.html

As far as I know, there is nothing else like it on the web.

fyi.

Regards,
Mike Jones
www.public-domain-materials.com
Tuesday, 29.Oct.2013
Fort Worth, Texas MERCA