* Shadow Length and Angle: The length of a shadow depends on the angle between the sun's rays and the object casting the shadow. The smaller the angle, the longer the shadow.

* Long Side vs. Short Side: When the long side of the box is facing the sun, the angle between the sun's rays and the box is smaller than when the short side is facing the sun.

* Result: With a smaller angle, the shadow will be shorter.

Think of it this way:

* If you hold a pencil straight up (like the short side of the box facing the sun), the shadow will be long.

* If you tilt the pencil slightly (like the long side of the box facing the sun), the shadow will be shorter.