The Fall
Hint: Sam is not who he appears to be.
The Answer: Sam is an ant. His lack of mass allowed him to float on the air currents to the ground.
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River Rocks
Hint: What factors exist around a drainage ditch?
The Answer: The landscape workers put a roll of felt under the river rocks, which allowed drainage from the heavy rainfall to lift up some of the river rocks and deposit them further down the drainage ditch.
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Marathon Runner
Hint: Count the days from beginning to end.
The Answer: Dean Karnazes ran 50 marathons in 50 states in 50 days.
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Tennis Tournament
Hint: Each player loses once.
The Answer: 127 Matches.
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The Tortoise
Hint: He got some help.
The Answer: Strangely, another tortoise helped him flip over.