Quiz on Volumes and Weights

Here's something to think about.........
When baking, recipes sometimes call for volume measurements like a cup for ingredients and weight measurements like grams or ounces. What would one do to express a volume in terms of weight or vice versa?
Can you think of situation where a person would need a recipe written ONLY with volumes OR weights? Hmmm... Think and let us know what you come up with.
(Another post soon to be made might give you a hint)