procena

1. estimate; valuation
   Po proceni stručnjaka, šteta iznosi milion evra. — According to experts' estimates, the damage amounts to a million euros.
   Banka je naručila procenu stana. — The bank ordered a valuation of the flat.
2. assessment; judgement
   To je bila pogrešna procena trenera. — That was a misjudgement by the coach.
   Ostavljam to vašoj proceni. — I'll leave that to your judgement.

A school grade is ocena, not procena.