Decide on your color pattern (the order for the colors of Jell-O you've selected), and begin by working with the color that will go on the bottom.
Boil 1 cup of water in the microwave.
Add 1 packet of Jell-O to the boiling water and stir until completely dissolved.
Pour ½ cup of this liquid into a 9x13 pan to create a "clear" layer, tilting pan for even coverage if necessary (see note).
Refrigerate until set (see note).
While the first layer sets, add ½ cup Greek yogurt and 2 tablespoons cold water to the remaining liquid Jell-O for the "cloudy" layer.
Pour the liquid for your "cloudy" layer on top of the completely set clear layer.
Refrigerate again until set.
Repeat this process with each color of Jell-O to create alternating "clear" and "cloudy" layers in each color you've chosen.
Refrigerate until serving.
