I remember being in 3rd or 4th grade and a visitor to the classroom posed this challenge for us.
A farmer has a fox, a chicken and a sack of seed. He needs to get all three safely across a river. The farmer has a small row boat to transport himself, the animals and the seed. A few problems. He can only take one thing in the boat with him at a time. Also, he cannot leave the fox alone with the chicken because, well, you can imagine what would happen. And, he can't leave the chicken alone with the seed, because, well, the chicken would get hungry.
No one else can aid the farmer. And neither he nor the animals can swim.
How can he get all three across safely without losing one or the other to a hungry appetite?
Answer revealed soon!