Receiving interest from a bank, dividends from stocks, etc.
Understanding the concept of separating "pesoles" (bad) from "pesoles"(bad). Ex. Separating recycling from the rest.
floor Drain with Hinges or Handle, Shelf in a Bookcase with Hinges, and the Use of a High Riser or Sofa Bed on Shabbos;
Various Halachas of Putting the Dishes into the Dishwasher;