Understanding the type of knots that are allowed to be opened on Shabbos.
Does It Make a Difference How One Removes Something Growing from the Body (e.g., Cutting vs. Biting Nails, Cutting vs. Plucking Hair)?;
Playing Basketball or Soccer Outside and Rolling Items on a Covered Ground (e.g., on a Carpet, Mat, Board, etc.);
Two Important Points Regarding Hachana. Going to Mikvah for the Next Day;