“教科书” means “textbook,” and “式” means “type.” Chosen to be one of 10 buzzwords of 2018 by monthly Chinese magazine Yaowen Jiaozi (Chew Over Words), this term refers to something that is very up to standard and can be used as a textbook example. In May this year, a short video of a Shanghai police officer punishing illegal actions went viral for being a good example for other police officers, which helped propel the popularity of the phrase. The term is rather neutral and can be used in either good or bad examples.
Zuótiān wǒmen yǒu ge nǚ tóngshì bèi qiúhūn le。Nánshēng zhǔnbèi le dàngāo 、xiānhuā 、qìqiú hé zuànjiè ，chǎngmiàn hǎo wēnxīn。
Yesterday one of my colleagues was proposed to by her boyfriend. The man got a cake, flowers, balloons and a diamond ring. It was super sweet.
Zhè kě zhēn shì jiàokēshū shì qiúhūn。Nǚshēng dāyìng le ba？
This is a textbook example of a marriage proposal. Did the girl say yes?
Of course she did.