

川で石を拾いました。
道に大きい石がありますよ。
この石は何ですか。
"いし(石)" is in the lesson "Nature" (Level 21), along with 11 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.