To turn certain words into plural forms, we can add たち to the end of a noun or pronoun. It can be written using hiragana, but is also sometimes written using kanji (達tachi).

たち is often used with personal pronouns such as 私watashi + たち = 私watashiたち (we, us), or あなた + たち = あなたたち (you, you guys).

It can be used to mark a group of people, e.g. 学gaku生seiたち (students), 子ko供domoたち (children). Of course, 学gaku生sei and 子ko供domo can be used on their own to mean students and children, so the key difference here is that たち implies there is a group in particular you are referring to.

The suffix ら (等ra) can also be used with some nouns to pluralize them, but as it can come across as very informal or direct it is safer to use たち when in doubt.

However, ら is used with 彼kare to make 彼kareら (they, them), which is more commonly used than 彼kareたち.

ら is also commonly used with これ and それ.

Breakdown of kono gakkou no kodomotachi wa totemo yasashii desu.