Ask students what is meant by keyword?
From Francine Egger-Sider:
Talk about tagging in social media- We can't really communicate if we all use different words for the same thing. Ex: how do you decide what to describe a cat:feline, tabby, cat, etc.
Definition of SH which is controlled voc as opposed to natural language for keyword
Use examples: death penalty vs. capital punishment
elderly people - older people
aged - older people
Using SH in reframing your keyword search can narrow your topic.
Then i show them in the databases, usually the SH are listed under the citation.