Like the coalface, the Chalkface is where the real, dirty, tough, hard work is carried out. If you work at the chalkface it means to work at the toughest end of education: standing in front of a class teaching, using a chalkboard to explain and elucidate. (Of course these days chalkboards have been replaced by whiteboards or interactive boards but the term is still used.)
Traditional teaching is known as Chalk & Talk – it means you stand at the chalkface and write and talk and write and talk… until your students fall asleep.
For more, see Chalkface – Chalk & Talk.