This section is not in the book. It is designed for my curious students, who want to know more.
It is useful to know parts of speech while learning Russian, because different parts of speech decline in a different way.
     There are 8 main parts of speech:  an adverb, an adjective, a conjunction, an interjection, a noun, a preposition, a pronoun, and a verb. 

 

      In Russian a noun, a pronoun, an adjective, and a verb decline.

      An adverb, a conjunction, an interjection, and a preposition stay the same. That is why it is important to distinguish them.

      Let’s have a look at them.

 

There are 10 of them (including Interrogative) in Russian:

 

я (I), ты (you-informal), он (he), она (she), оно (it), мы (we), вы (you-polite), они (they), кто who), что (what)

Russian Personal Pronouns decline depending on the gender, number and case.

 

Personal Pronoun replaces a noun already mentioned in the text or dialogue.

 

Это Иван. Он учится в университете. = This is Ivan. He studies at the University.

 

Это книга. Она интересная. = This is a book. It is interesting.

 

То окно. Оно большое. = That is a window. It is big.

 

As a Personal Pronoun stands for a noun, it declines similar to it (according to gender, number and case)