Governor of Delta State, Hon. Sheriff Oborevwori has challenged teachers to continuously upgrade their knowledge and teaching skills. He gave the charge on Saturday while speaking at this year’s celebration of Teachers’ Day held in Asaba. The governor was represented at the occasion by his Deputy, Sir Monday Onyeme. “Teachers and educationists must continuously upgrade their knowledge and teaching skills and adapt to changing situations very quickly. “The role of the teachers in nation building cannot be over emphasised; a nation is built by its citizens; citizens are taught, trained and mould…