O Δάσκαλος: ουσιαστικός ή ουσιαστικό countable / uncountable???

What makes a teacher outstanding

In relation to cans of drink, these such of performative measures work. But the performance of schools is much less easy to measure. Examination grades, at first, appear to be the most obvious way to assess, and compare, how well school X and school Y are doing. Yet, the two schools might be in completely different areas, serving completely different people...