

今日は日曜日なので、学校は休みです。
雨なので、出かけません。
明日はテストなので、早く寝ます。
"なので" is in the lesson "Conjunctions" (Level 32), along with 13 other useful words. LinDuo has 180 topic lessons like this one, 2,379 words in total. Every word has an illustration, a transcription and pronunciation in a female and a male voice. Just 10–15 minutes a day is enough to learn them all. Free, and works offline.