OK, I'm curious. I couldn't find タ形 in the dictionary, but I figured out that it's probably used the way we Japanese learners talk about "〜な adjectives" for words like きれいな. In other words, タ形 is used for words like 食べた. (And by searching the web, it's obviously a word that people use in Japanese when discussing this conjugation, though it doesn't seem to be used much written this way in English learning materials.) I'd suggest using "〜た Form". I think that's what my Japanese teacher generally uses. (And if the student is at the level where they are just learning this form, it's unlikely that they'll be familiar with the meaning and reading of 形, unless they already speak Chinese.) So, let me attempt to offer an edited version of your sentences. (And I guess you changed your mind about 私は本を読んだ, so I'll use the "library" version. *** "〜た Form" is a verb conjugation form where the verb ends in た or sometimes だ. A sentence with the structure [Subject] + [Verb in 〜た Form] can be used to talk about past events. For example: 私はとしょかんに行った。("I went to the library.") Note that this form is not used in situations when you want to sound polite. [I'd suggest leaving this qualification for later, because it requires further explanation.] In this lesson, we will learn how to use 〜た Form + ことがある／ことがない to express "having done something" or "not having done something." 〜た Form usage to express the simple past will be covered in the next lesson. *** It's challenging to write about these things especially for beginner level students, isn't it? I look forward to more.