We sewed dust cloths in home economics class.
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means sew, so the verb version is to sew or to stitch.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You haven't learned this reading yet, so here's a mnemonic to help you:
You have to sew yourself some clothes because if you don't you'll be completely nude (ぬ). You don't want anyone to see your bits! Sew quickly!