Keep the Heat
If you're sending your budding foodie to school with a warm soup, fill a thermos with very hot water and wait a few minutes. Drain the water, then add the hot soup to the thermos and seal—taking the time to heat up the thermos beforehand will ensure your kid is greeted with warm comfort come lunchtime. Insulate hot or cool foods away from each other to make sure neither one ends up at an unsafe temperature. If you're cooking or heating up a dish before slipping it into the lunchbox, give it a chance to cool completely before packaging it up. Once it's packed up, keep the lid off until the very last second; this prevents condensation and makes the lunch container easier for tiny fingers to pry open.