School exercise (5)
I believe the answer is:
train
I believe this is a double definition.
'school' is the first definition.
(training is a kind of schooling)
'exercise' is the second definition.
(training is a kind of exercising)
(Other definitions for train that I've seen before include "Retinue; sequence" , "Procession" , "Tailpiece of bridal gown" , "tutor" , "Number of eg carriages in a line" .)