上 / 下 / 里 / 外 / 前 / 后【shàng / xià / lǐ / wài / qián / hòu】

A word telling you where something sits goes after the noun, not before it. English has prepositions; Chinese has these.

The order is the reverse of English throughout: 书包里 is bag-inside, and that is the shape to get used to.

With 在

Leaving the localizer off gives Shū书zài在zhuō zi桌子, which is wrong. An ordinary noun is not a place until one of these turns it into one.

Place names need nothing

北京, 学校, 家 and 商店 are places already. 在北京, not zài在Běi jīng北京lǐ里.

The long forms

上面, 里面, 前面, 后面 and 旁边 can stand on their own as nouns, where the short forms cannot.

里 does not attach to everything

Some nouns take 上 where English would say "in": 车上, 飞机上, 路上, 书上. A page and a vehicle are surfaces in Chinese.