 If you liked GTO |  ...then you might like Koko wa Ima kara Rinri desu. |
Episodical storytelling about a cool teacher that takes on problem children in his class and helps them with somehow unconventional methods.
Both have a teacher solving problems about their students. GTO has more comedy though.
report Recommended by FlowerIris
both include a teacher who gets involved with their student's lives and struggles.
Explained short story told, "We shall now begin ethics" is a Seinen version of the Shounen GTO, both revolve around two amazingly encouraging MC teachers. Based on the target audience, "Koko wa-" doesn't contain any action nor comedy, but rather philosophical and psychological aspects. I'd genuinely recommend "Koko wa-" over GTO since it's only 30 chapters so far (heavily dialog-based though) and the MC (Takayanagi) actually interacts with the entire class, individually, regarding their problems/concerns about life - not to mention Takayanagi is so daddy material too lol