A slow cooker is a big help for people who don't have the time or desire to be in the kitchen. Combine your ingredients into a slow cooker in the morning and you can come home to a hot, home-cooked meal, all without the cooking. Many slow-cooker covers are made of glass, which can be fragile. If you place a hot cover on a cool counter, the temperature shock can crack and ruin the lid. If you plan to use the cooker again before you have a chance to get a replacement lid, you'll need some kind of cover to use in the meantime to help contain the heat.
Replacement Lids From Around the Kitchen
Try other lids and pot covers from your cooking supplies to see if any fit snugly on your slow cooker. A cover needs to help prevent heat and steam from escaping, and should not be so large that it can slide off. If you can't find another lid, see if you have a heatproof plate or serving platter that's big enough to place over the opening. Use the slow cooker as usual.
Aluminum Foil
Cut two pieces of heavy-duty aluminum foil, each a little larger than the width of your slow cooker. Before turning on the slow cooker, lay the two layers of foil over the top and crimp them gently around the sides of the slow cooker for a tighter fit. It's important to crimp the foil around before turning the cooker on so you don't burn your hands.