IZI - Rus tili. Oson. is a free educational Android application developed by IZI Study. The app is designed to teach Russian language learners through theory, practice, and continuous repetition. The program consists of three parts: vocabulary, grammar, and practice.

In the vocabulary section, learners will be introduced to new words, each with its unique groupings. Each word is accompanied by an illustrative image, an associative text, and the correct pronunciation. The app also provides learners with exercises to help them remember the words easily.

In the grammar section, the app introduces learners to new grammatical rules in a structured way. The app presents sentence structures in block form, which makes it easy for learners to understand how sentences are constructed. The grammar section also includes several simple exercises to help learners practice the new rules.

In the practice section, learners are given practical exercises to test their understanding of the vocabulary and grammar they have learned. The exercises include activities like sentence creation, translation, dialogues, comprehension, error detection, and more. Additionally, the app provides learners with review exercises from previous lessons, which helps them to reinforce their knowledge.