Zài / wǒ / gěi / lǎoshī / sòng / huā / zhè / jù / huà / lǐ / lǎoshī / shì / jiànjiē / bīnyǔ

在“我给老师送花”这句话里，“老师”是间接宾语。

In the sentence “I give flowers to the teacher,” “the teacher” is the indirect object.