

あの男の子はだれですか。
公園で男の子が遊んでいます。
うちには男の子がいません。
"おとこのこ(男の子)" is in the lesson "Family 1" (Level 1), along with 12 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.