[Answered ]-No reverse match with unexpected arguments

In your url regex you are using \w+ where as the argument is yoga-class. The - does not belong in \w+ character class hence the error.

You need to update this:

url(r'^page/(?P<slug>\w+)/$', PageOrSinglePost.as_view(), name='page'),

to this:

url(r'^page/(?P<slug>[\w\-]+)/$', PageOrSinglePost.as_view(), name='page'),