text: There are a whole host of ways that heavy cast iron skillets may be better than (or worse) than using a lightweight skillet, but given that this is probably a question that wants you concentrate of physical properities of materials  I will limit my comments to that area.\n\nA heavy cast iron skillet has more MASS than a lightweight skillet of any kind. Therefore it will heat up more slowly and transfer changes in heat less rapidly. This may be an advantage when cooking foods that one wants evenly browned/seared, as those kinds of task require lots of even heat. This same "slow to heat & cool" property might be a disadvantage when trying to quickly boil or evaporate liquid. It would also be a disadavantage when trying cook delicate foods quickly, as in making candy, where precise temperatire control helps to prevent overcooking.\n\nFurther, uncoated cast iron is chemically reactive -- it will rapidly oxidize/rust and so must be coated with oil to prevent it from deteriorating. Even using it to cook foods that are acidic (such as tomatoes or vinegar) will also cause chemical interactions.