Do you have any old grungy pennies around the house? I’ll bet you do. Check under the couch cushions. Oh. Is it just my couch that collects money? Try the cup holders in the car. Still just me? We’ve been studying the first 12 elements on the periodic table, and this little experiment is an easy lesson with some pretty cool chemistry going on. Bonus, it’ll make your gross pennies look brand-spankin’ new. Like magic. Disclaimer: Vinegar is (apparently) the absolute worst smell on the planet. According to my kids, it may kill you with prolonged exposure. You may want to add “noseplug” to your list of materials.