Discover the science of refraction! Learn why a straight pencil looks bent when placed in water by observing how light changes speed and direction.

Tools

• pencil (1 piece)

Materials

• clear glass or plastic tumbler (1 piece)
• water (approx. 200ml)
• small coin (1 piece, optional for extra experiment)

Safety

• Adult supervision is recommended when handling glass containers to prevent breakage.

Steps

1. Fill the clear glass or plastic tumbler about 3/4 full with water.
2. Hold the pencil vertically and slowly slide it into the glass of water.
3. Step back and look at the pencil from the side of the glass, ensuring your eyes are level with the water line.
4. Observe how the part of the pencil submerged in water appears to be shifted or 'bent' compared to the part above the water.
5. Gently rotate the pencil to see that the 'bend' stays in the same place regardless of the pencil's angle.
6. Optional: Drop a coin into the bottom of the glass and try to touch it with the pencil to see how the refraction tricks your eyes about the coin's actual position.