De or het scholencompetitie?

The correct Dutch article is:

de scholencompetitie

Rule Words ending in -tie and -sie: almost always de. See the rule

How to use scholencompetitie

the scholencompetitiede scholencompetitie
this scholencompetitiedeze scholencompetitie
that scholencompetitiedie scholencompetitie
our scholencompetitieonze scholencompetitie
your scholencompetitiejouw scholencompetitie
every scholencompetitieelke scholencompetitie
which scholencompetitie?welke scholencompetitie?
a big scholencompetitie / the big scholencompetitieeen grote scholencompetitie, de grote scholencompetitie