A large foam block and a small rock are placed on a balance scale. The rock's side goes down. What does this tell us?
AThe balance must be broken — bigger objects should always weigh more
BThe rock is heavier even though it is smaller, because weight and size are different attributes
CThe foam is heavier because it is bigger and takes up more space
DThe objects weigh about the same, since one is big and one is small
The rock going down means it exerts more force on the scale — it is heavier. This directly demonstrates the key insight: size and weight are separate attributes. A small rock can be heavier than a large piece of foam because weight depends on what the object is made of, not how much space it takes up.
Question 2 Multiple Choice
A child wants to find out which of two objects is heavier. Which approach is best?
AChoose the one that looks bigger — bigger always means heavier
BChoose the one with more colors — colorful objects tend to weigh more
CHold one object in each hand and feel which pulls down more, then confirm with a balance scale
DMeasure how tall each object is — taller objects weigh more
Weight is something you feel, not something you see. Holding objects and feeling which pulls your hands down more gives a direct sense of weight. Confirming with a balance scale makes it precise. Looking at size, color, or height tells you nothing reliable about weight.
Question 3 True / False
A small metal bolt is heavier than a large balloon full of air.
TTrue
FFalse
Answer: True
Yes — this is true and is one of the most important counterexamples for this concept. The balloon is far larger but weighs almost nothing; the bolt is tiny but dense and heavy. Weight depends on what an object is made of, not how big it is.
Question 4 True / False
If object A looks bigger than object B, object A should weigh more than object B.
TTrue
FFalse
Answer: False
This is the most common misconception about weight. Size and weight are different attributes. A large piece of foam can be much lighter than a small rock. You must always hold the objects or use a balance scale to determine which is heavier — you cannot tell just by looking.
Question 5 Short Answer
Why can't you figure out which of two objects is heavier just by looking at them?
Think about your answer, then reveal below.
Model answer: Because size and weight are different attributes. A big object can be light (like a balloon) and a small object can be heavy (like a metal bolt). Weight depends on what an object is made of, not how much space it takes up. You have to hold the objects or use a balance scale to compare their weights.
The key insight is that weight is a separate measurable attribute from size, shape, or color. Many physical properties — density, material composition — affect weight independently of size. This is why direct measurement (holding or balancing) is the only reliable method.