Everyone needs a method of storing leftovers. That may be why, slowly but surely, a collection of takeout containers has amassed in your kitchen. The only trouble is that different containers from different sources rarely match in size. That makes it difficult to use the limited space in your fridge most efficiently by stacking containers on top of one another. The simple secret: Buy sets of containers that are all the same size. The plastic ones come cheap, but you can actually save money if you invest in containers made of glass. Unlike plastic, glass doesn't stain or absorb odors. Handle yours carefully, and they can last forever. Available at Amazon; $10.99 per set of three 12-ounce containers.