If a fixed product is not exciting enough for you you may be interested in a variable product. Variable means the returns can vary. Think of variables as similar to your 401k. The advantage is you can take 1 dollar and turn it into 1,000. The disadvantage is you can take 1,000 and turn it into 1.
Some folks will tell you these are a good option for younger teachers because you have the time to lose today because you can make it up years later. WOW! This is pretty silly. Your money is yours and you should never be content to lose some now in the hope to win some later.
Variables come in all shapes in sizes. Some are index tied, others are small cap or others are large cap.... the short is they are all risky, and I encourage you to think twice before choosing one of these.
Also, if your 401k is variable- no sense putting all your eggs in this basket. Diversify.