Refers to a unit of study or assigned school tasks; slightly formal, often used in academic or curriculum contexts.
今日の学課は難しい内容だった。
Today's lesson was difficult.
彼は毎日、学課の復習を欠かさない。
He never misses reviewing his schoolwork every day.
Compound of 学 (learning) and 課 (lesson, section). The reading がっか is a standard on'yomi combination.