Is one allowed to wear shoes that have letters, numbers or pictures on the bottom.
ודבר דבר (Dabair Davar): Mentioning Something That Somebody Will Do After Shabbos When It's Not Allowed to Be Done on Shabbos Itself;
Giving Out Tickets to Children for Learning Well. If One Finds a Mistake in a Sefer on Shabbos. Index Cards for an עליה;
Understanding the Concept of Removing a Creature from Its Life Source;