

これは私のかさです。
田中さんのお母さんは先生です。
あれは誰のかばんですか。
"の" is in the lesson "Prepositions" (Level 36), 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.