Doch is a difficult construct to nail down in German because it is always context dependent. Seeing as we don't know the situation it could have two possible meanings according to duo lingo
The doch is here for emphasis.
We DO need more teachers.
Or the doch can also be used as a 'however'
There's a nice discussion of "doch", with some excellent examples, particularly the usage by the bickering schoolboys, here: http://yourdailygerman.wordpress.com/2012/02/27/meaning-of-doch/
I may be wrong, but I believe the seperation between doch as emphasis (do) vs however, is only that however distances from the opposing whereas do and such emphasis giving words like it build up the claim, rather than being used in a chiefly contrarian manner. So I would expect that german sentences with negations (nicht, kein, nein) would be the ones which would have doch translate as however.