STDEV with IF

[Rod]

I have a SS with student standardized test results for
different classrooms listed together. I want to check the
range c3:c43 against a52 to separate out only those scores
for that given room and find the standard deviation for
the scores. The problem comes if there is an empty cell
(no score) for a student in the room; the formula sets a
zero as the lowest score and figures the STDEV based on
that compared to the highest score. I have tried the
following function entered as an array. Any ideas?
=STDEV(IF($C$3:$C$43=$A$52,$U$3:$U$43))

 

[Rod]

Say, I used Peo's suggestion from my MIN w/IF and simply
changed the MIN to STDEV and it worked!!! Here is what he
suggested and the alteration: