eyes naturally focus on the water level.
When four glasses appear to have the same level, the immediate assumption is that they contain the same amount of liquid.
But the objects inside the glasses change the amount of available space.
This is a great example of why visual puzzles can be deceptive: what you see first isn’t always the whole story.
The Science Behind the Trick
Imagine removing every object from its glass while keeping the glasses otherwise unchanged.
The glass that contained the smallest object would have the least displaced volume. If the visible water levels were initially the same, that glass would therefore have the greatest volume of water.
This is the basic idea behind displacement and explains why the paper clip gives Glass A the advantage.
Did You Choose Correctly?
If you picked Glass A, you spotted the important detail that many people overlook.
If you chose
