Here's why:

* Volume measures the amount of space a substance occupies. We typically use units like cups, pints, quarts, or liters for measuring liquids.

* Mass measures the amount of matter in a substance. We typically use units like grams or kilograms for measuring solid ingredients.

Lemonade recipes generally call for specific amounts of water by volume (e.g., 4 cups of water), not by weight. This ensures that the right amount of water is used to dilute the lemon juice and sugar, regardless of the temperature of the water.