Which weighs more: a gallon of liquid water or a gallon of ice?
(With "weight" meaning, weight on the same planet, at the same location -- so literally, "which has more mass?")
Both are of same weight, 1 gallon.
You are enjoying your breakfast after having put some salt on your scrambled eggs when your nerdy brother presents you with an ice cube floating in a glass of water and a short length of string. He challenges you to remove the ice cube from the glass using the string without tying any knots.
What strategy do you use to remove the ice cube from the water glass?
We all know that if you weigh yourself on the moon, it is less than your weight on the Earth. Can you tell me something that actually weighs more on the moon than on Earth?
On a hot summer day by a lake you are determined to build a boat made of ice, using a refrigeration unit and a large mold in which you can pour water. Nearby you notice an Egyptian mummy resting on a pile of wood pulp.
What is the best strategy for building an ice boat that will not melt before you sail it across the lake?