How about a culture lesson on grandmother-sayings. For example, two of my grandmother's sayings are "An apple misused is an apple bruised" and "If there's an egg in the house there's a meal in the house."
Or you could do "strange habits from the old days". Rural NZ houses collect water from the roof and store it in a big tank, so you're always in danger of running out. My grandparents had a well put in about 15 years ago, so they have a neverending water supply, but they still have deeply ingrained water-using habits. No showers longer than 3 mins. When they wash the dishes they put a basin into the sink and fill it with 2 inches of water and no more. It looks like soup by the time the dishes are done.
My grandmother scrapes all the bacon fat or runoff from a roast, complete with little floating fragments of meat, into a can and saves it for cooking later. Sometimes it sits there on top of the stove for weeks or months. A friend's Jewish grandmother fled Poland as a young woman, and she always keeps the kettle full of water as a secret stash because you never know when you're going to lose your water supply.
