He said the practice made classrooms dull and appealing to only average students.
Mr Ashiboe-Mensah gave the advice at a day’s workshop for selected Basic School teachers in Ho on: “Effective Teaching for Classroom Management.”
He asked them to make classrooms “intellectually friendly” and create learning experiences for pupils.
Mr Ashiboe-Mensah said teaching was not a “routine job” hence it was improper for teachers to get involved in other jobs after school.
“If you want to do a side job, it should be teaching and not trading or any other business that will not allow you to concentrate and prepare lesson notes,” he stated.
Mr Ashiboe-Mensah said though those other jobs could be economically rewarding, they would be detrimental to the academic development of schoolchildren and must be avoided.
Similar professional development training workshops were held in nine districts in the Volta Region and expected to help improve performance of pupils in the Basic Education Certificate Examination.
The engagements are also to develop quality assessment and supervision competences in basic education.