纲 (gāng) here is short for
教学大纲 (jiàoxué dàgāng, syllabus/curriculum outline).
超纲 became a household word during China's tutoring crackdown — extracurricular schools were accused of
超纲教学 (chāogāng jiàoxué, teaching beyond grade level) to boost test scores, prompting the 2021 "double reduction" (
双减, shuāngjiǎn) policy.
