Your teacher meant 私は. Although it is said like "わ",　は is how it written as a the topic marking particle. Avoid saying 私は when it is not necessary. Japanese is not like English where leaving out "I" can get confusing, and is grammatically incorrect. If I were to say to you "Next week read books" that would sound strange and you might think I am commanding you to read books next week. But it clear if the sentence is about you in Japanese, you don't need the 私は. 来週に本を読みます。 If I were to tell a story where I went shopping, and describe each event in order, saying 私は for each sentence, is not needed. The reader knows who I am talking about, I don't need to clarify it is me who is participating in each action.