Odds are our great grandparents used a lot of metal and glass containers for storing food. Polyethylene was formulated in 1942. Prior to that the only choices for food storage were metal, glass, cloth, earthen ware, or root cellar type storage. One of the pioneers in the field of developing food storage was Earl Tupper, a chemist for DuPont chemical. He started a movement in plastic storage that has become a common name in households across America. Tupperware. You can read a little more about him and the process here.
In my humble opinion, Tupperware is great, but over priced for what you get. 
Don’t get me wrong, a well cared for Tupperware storage dish will last several lifetimes. I have one that I am pretty sure is my grandmothers. I kind of discount the long term life of them as I am apt to loan them out or leave them at work and that flips the payback equation greatly. I use the much lower priced GladWare style almost disposable containers.
You can save a lot on the disposable ones by buying a store brand. A local retailer here in the North Central US is Meijer. They have a house brand of the disposable containers that are about 50 cents cheaper than the Glad brand and last just as long. It bothers me a little to think that I am deciding to use a more disposable item, but the reality is I tend to use the things to death. If a lid cracks I will use it as a saucer under a pot for retaining water. If a container cracks it will often get wrapped with duct tape and set on a shelf in the garage to hold the occasional screws or nuts that I tend to accumulate. The beatup ones are useful to keep parts separated when disassembling something and you need to remember where the screws went and in what order.
For food storage they are good for keeping leftovers in the refrigerator, keeping herbs, or short term storage of dry goods. I personally consider less than ideal for long term storage whether in the freezer or on the shelf. The seal produced between the container and the lid is almost liquid tight, but certainly not air tight. I will use them in the freezer for storage of broths and other liquids that I think I will use before freezer burn can become an issue.
A recent issue has come up regarding the safety of storing food in plastics and the leeching of BPAs into the food. Glad has an official statement on the presence of BPAs here. They are officially claiming there are none. Good Housekeeping magazine did an investigation on this and found no problems with the Glad brand containers. Their investigation appeared to be very thorough and on those they found problems with they further went on to see if there was any actual leaching that occurred. Take the time and read the article. These little gems appear to be safe. Even if you microwave in them.
You may wonder why I would use these over glass or metal containers. Honestly, I’m not quite sure. I feel a little odd sending my youngest daughter off to school with a mason jar full of carrots, but it just seems natural to send her off with one of these small containers of carrots. I think the mason jars would have the largest potential for reuse, but that assumes that the jar is cared for and not nicked, cracked, or broken. The Glad-ware is certainly reused more often than a baggie.
Other uses of the containers:
- Premeasure all the dry ingredients(except yeast) for a loaf of bread. Dump this in the mixer with the water and milk and you might save yourself 5 minutes for your bread.
- Open a bag of pretzels for the kids lunches and premeasure them into the containers.
- Make a pot of pudding or Jello and put in these for taking in school lunches.
- Open a quart of last summer’s peaches and divide up between several small containers for a perfect take along snack.
- Old one on their last legs are perfect for catching grease out of frying pans.
- Premeasured storage of pastas for faster dinners.
