While you dream of having a commercial-grade, high-end oven, what you've likely got is whatever cheap oven your landlord purchased 700 years ago. Sure, you can turn the dial to your desired temperature, but you know from experience (and many batches of burned cookies) that you can't trust that thing. That's why it's absolutely essential to have an oven thermometer, like this trusty one from Rubbermaid.
Crafted out of sturdy stainless steel, the tiny thermometer will stand at the bottom of the oven or hang from one of the racks, providing you the exact temperature every time, and helping to avoid having any more cooking disasters because of your unreliable oven.
Need more convincing? It's a number-one best seller on Amazon and has great user reviews, so even if you can't count on your oven, you know you can count on this guy.
More kitchen essentials: 25 Classic Kitchen Tools That Every Home Cook Needs