lǎo shī shuō xià jié kè jiāo tōng cháng bú shì jīn tiān jiāo ér shì xià yī cì shàng zhè mén kè shí jiāo

老师说“下节课交”，通常不是今天交，而是下一次上这门课时交。

When the teacher says 'submit next class', it usually means not today, but the next time this class meets.