Put the blueberries in a strainer and pick out any green or shriveled berries and remove any stems. Rinse them under cold running water and allow the water to drain out.
Pour the clean berries into a small pot that has a lid. Measure in the juice and agave. Mix the berries with a wooden spoon. Cover the pot and cook the berries over medium low heat. Stir the sauce after about four minutes. Cook the sauce for four more minutes, until the berries burst and make some juice. Turn off the stove and let the sauce stand uncovered for at least three minutes so the sauce can get thick. Serve blueberry sauce over any of your favorite foods.
Children should be supervised by an adult.