What is the case of «مُعَلِّمِي» in «رَأَيْتُ مُعَلِّمِي الْمَدْرَسَةِ»?

Noun Case Classes: Type 6 — Sound Masculine Plural and Related Forms

• Nominative with wāw
• Accusative with yāʾ
• Genitive with kasra
• Indeclinable with sukūn