If it is a proper blackboard for the use of chalk, full marks for that one,

In Scotland's high schools, blackboards have been banned for a good few years for health reasons - there is a risk of teachers developing cancer from chalk dust. I discovered this during the SARS scare in the PRC. I had returned to Scotland for a vacation just before the SARS outbreak, and decided to obtain employment as a supply teacher of maths. I had to get an enhanced disclosure police check first! I had got it for Scotland, not for China! I taught maths on the island of Mull at Tobermory High School for a few days to fill in for the head of department, who had an op for testicular cancer on the mainland.

Personally, though, I prefer blackboards to whiteboards. I find my writing goes to hell on the latter, using marker pens of course.