上课

Pinyin: shàng kè
Meaning：Take class; give a lesson
Sentence: 因为流行性感冒全校停止上课。The school was closed because of the flu.

More:

上：

Pinyin: shǎng,shàng
Meaning: On; upper
Radical: 一
Stokes: 3
Traditional: 上
Common words/Phrase:
上午 [shàng wǔ] 【morning】
上次 [shàng cì] 【last time】
上班 [shàng bān] 【to go to work】
上市 [shàng shì] 【to be listed】
上传 [shàng chuán] 【upload】

课：

Pinyin: kè
Meaning: Lesson; class
Radical: 讠
Stokes: 10
Traditional: 課
Common words/Phrase:
课程 [kè chéng] 【course】
课题 [kè tí] 【topic】
课堂 [kè táng] 【classroom】
课表 [kè biǎo] 【school timetable】
课文 [kè wén] 【text】