How long does a knot have to be tied to be considered a "קשר של קימא". (Knot of permanence).
how to work with opening up twist ties;
Giving Out Tickets to Children for Learning Well. If One Finds a Mistake in a Sefer on Shabbos. Index Cards for an עליה;
How to Deal with a Power Outage If It Occurs on Shabbos;