How long does a knot have to be tied to be considered a "קשר של קימא". (Knot of permanence).
The Concept of Trapping a Slow-moving Creature (e.g., Turtle, Caterpillar);
Many Various Examples of Actions One Might Not Be Aware Of Which Could Fall Under the Melacha of Memachaik;
how to work with plastic tablecloths;