The teacher instructed the students on how to operate the lab equipment properly.

instructed 是动词 instruct 的过去式，instruct 由前缀 in-（表示"向内"）和词根 struct（来自拉丁语 struere，意为"建造、安排"）组成，字面意思是"向内构建"，引申为"教导、指导"的意思。