A physics teacher used to enjoy tricking his students into learning science facts. One day, he placed an 8-ounce glass filled with water on a table. He then produced 2 straws; one straw he placed into the glass of water and the other he held outside the glass.

"Class," he said, "I am willing to fund a pizza party for the class if any one of you can drink this glass of water in 5 minutes using only these two straws." The class was amazed; this would be an easy task for any of them. "There are a few conditions," he continued. "You must drink using both straws at the same time. You must drink using slow and steady draws. You cannot block or obstruct either straw in any way. You cannot lift or tilt the glass off of the table. And finally, one straw must remain outside of the glass."

The class selected their champion and felt confident that they would be enjoying pizza at the same time next week. Five minutes later, the champion returned to his seat, defeated, and the class sat with jaws agape. Being a good sport, the teacher still bought pizza for the class the next week, confident they would never forget the lesson he taught them.

Why did the champion fail?