Your oven grill is a useful kitchen tool, but doesn't necessarily offer even performance throughout. America's Test Kitchen shows us how to make a map of your grill so you'll never burn or undercook your food again.
All you'll need for this is a few slices of white bread. Heat the grill (or broiler, as the Americans put it) and put the bread under the grill for a few minutes. When you look at the bread, you'll have an idea of whether your griller works evenly or has hot and cold spots, based on how brown the bread becomes.
America's Test Kitchen suggests you take a photo of the pan when you're finished so you'll always be able to remember where you should or shouldn't rotate, or which areas will cook faster than others. It's a very simple trick, and you'll have a lot of toast when you're finished, but it's definitely worthwhile if you've been getting inconsistent results from your grill.
How to Make a Broiler Map [America's Test Kitchen]