Applied comparison across six forms

Demonstratives — forms, syntax and usage

Compare all six referent categories:
هَذَا الْمُعَلِّمُ — masculine singular.
هَذِهِ الْمُعَلِّمَةُ — feminine singular.
هَذَانِ الْمُعَلِّمَانِ — masculine dual, nominative.
هَاتَانِ الْمُعَلِّمَتَانِ — feminine dual, nominative.
هَؤُلَاءِ الْمُعَلِّمُونَ — masculine plural.
هَؤُلَاءِ الْمُعَلِّمَاتُ — feminine plural.

First identify the referent’s gender and number; then determine syntactic case from the clause.