Beansprouts are very easy to grow at home! There are a few ways to grow bean sprouts such as alfalfa, radish, etc. The following is how to grow mung beans. Be sure to buy the mung beans (I bought a bag of green mung beans in an Asian store in New Jersey last summer) that is intended for eating and not for planting.
1/4 cup of dry mung beans
Place the mung beans in the Mason jar. and fill it half way up with lukewarm water. Cover with a piece of cheesecloth and the screwing part of the jar lid. Place under the sink or anywhere it is dark and dry.
The next morning pour the water in a bowl. This nutritious water can be used in drinks, cooking or just watering plants. Do not waste it.
Cover the jar with the cheesecloth or a small screen and tighten with the jar screw band. Be sure to rinse the beans a few times a day (again, do not waste the rinse water).
Be sure the jar is tilted when it is resting. The jar should be returned to the warm dark place. If left on the window sill, the sprouts will be green because chlorophyll will start to develop. In a day or so you will have sprouts for eating.
Note: I learned this method from Organic Gardening in Hawaii by Richard L. Stevens.