Pick one idiom, write down the meaning, research the origin of the idiom, and use the idiom in a headline sentence. For example: Just sit down and do your homework! Let's not make a mountain out of a molehill.
Helpful websites: idioms dictionary, Wiktionary, phrases
Pull yourself up by the bootstraps
Mind one's p's and q's
Make a mountain out of a molehill
Pass the buck
Pot calling the kettle black