De or het schaakopening?

The correct Dutch article is:

de schaakopening

Rule Words ending in -ing: almost always de. See the rule

How to use schaakopening

the schaakopeningde schaakopening
this schaakopeningdeze schaakopening
that schaakopeningdie schaakopening
our schaakopeningonze schaakopening
your schaakopeningjouw schaakopening
every schaakopeningelke schaakopening
which schaakopening?welke schaakopening?
a big schaakopening / the big schaakopeningeen grote schaakopening, de grote schaakopening