At first glance, the puzzle looks incredibly simple.

Four identical glasses labeled A, B, C, and D appear to contain the same amount of water. But inside each glass sits a different object.

Your challenge is to answer one question:

Which glass actually contains the most water?

The puzzle seems easy at first… until you start thinking more carefully.

The Four Glasses

Each glass contains a different object:

• Glass A contains a paperclip
• Glass B contains a baseball
• Glass C contains an eraser
• Glass D contains a wristwatch

At first glance, many people choose based only on how “full” the glasses appear.

But appearances can be misleading.

This puzzle is really about one important scientific idea:

displacement.

The Important Detail Most People Miss

Whenever an object is placed into water, it takes up space inside the glass.

That means the larger the object, the less room remains for water.

So even if the water level looks similar in all four glasses, the actual amount of water changes depending on the size of the object inside.

That tiny detail completely changes the answer.

The Correct Answer

The correct answer is:

Glass A.

Because the paperclip is the smallest object, it displaces the least amount of water.

That means Glass A contains more actual water than the other glasses.

Larger objects like the baseball take up far more space, leaving less room for water even though the level appears the same.

Continue to the next page to discover what your choice might reveal about your thinking style →