Understanding the history and the purpose of the blech. The problem with agitating the fire or stoking the coals. Today's equivalent prohibition: she'hiyah (maintaining). Covering the controls of the stove. Crockpots, inserts, coverings and ovens. Important guideline: Everything should be fully cooked before Shabbos! Opening an oven door on Shabbos. The conditions of returning a pot of fully cooked food onto the blech: intention, holding, covered flame, original vessel, temperature. The three areas of the blech: directly over the fire, yad soledes bo (would burn my hand but not really hot enough for cooking), warm (but not yad soledes bo). Rules for moving pots around on the blech. Mechzeih kebishul - when it "looks" like cooking.