River Crossing

1. Form small teams of 2 to 5 people.
2. Challenge each team to solve an imaginary puzzle:
3. Using a small rowboat, how can they transport a chicken, a fox and a bag of corn to the other side of the river in as few moves as possible.
4. To govern fair-play, the solution must acknowledge three critical parameters:
   – The rowboat can only carry one person and one item at any point in time.
   – The fox and chicken cannot be left alone; and
   – The chicken and the bag of corn cannot be left alone.
5. Describe the step-by-step solution to get all three items safely to the other side of the river.
6. Allow ample time for discussion and trial-and-error.

This is one of those classic river-crossing conundrums which typically has only one answer. Yet, as with so many group initiatives, the value is found in the journey and not so much the destination.

Oh, and don’t think too hard about the circumstances – it’s hypothetical, and is designed simply to stimulate critical thinking. That is to say, don’t ask why, it’s not real.

Given the discussion and critical thinking required, I like to form lots of small groups of 2 to 5 people to tackle this puzzle.

In your set-up, either ask your group to imagine five primary elements – a woman, a rowboat, a chicken, a fox and a bag of corn – or provide some form of prop or toy to represent each.

Explain that the woman has a dilemma – she needs to get the fox, the chicken and the bag of corn across to the other side of a river in as few moves as possible. She has a rowboat, but it can only carry her and one other item at a time.

Her dilemma is clear – she cannot leave the fox and the chicken alone together (the fox will eat the chicken,) and she cannot leave the chicken with the corn (the chicken will eat the corn.)

So, challenge your group(s) to identify a solution that gets all five elements safely to the other side of the river. How does the woman do it?

Allow ample time for your groups to discuss their ideas and perform lots of experiments.

Okay, here’s the solution:

To begin, the woman and the chicken cross the river together. The fox and corn are safe together.

Once on the other side, the woman leaves the chicken and returns to the fox and corn. She takes the fox across the river, and since she can’t leave the fox and chicken together, she brings the chicken back with her (that’s the trick which many groups do not think of.)

She cannot leave the chicken with the corn, so she leaves the chicken and rows the corn across the river and leaves it with the fox.

Finally, she returns to pick up the chicken and rows across the river one last time. Voila!

If your group enjoys tackling this problem, take a look at the Variations tab for three more challenging puzzles.

The key move of returning the chicken to the starting side (even though it had successfully traversed the river) may open lots of valuable discussion about the notion of taking two steps forward and one step back. Or, the notion of making decisions for the greater good.

Expect your group to (a) lament the improbability of this situation and/or (b) suggest a whole raft of innovative ways to keep the fox away from the chicken and the chicken away from the corn (eg fences, sealing the bag, etc.) Applaud their creativity and encourage them to find a solution, as hypothetical as it is.

• Jealous Partners River Crossing: Three married couples must cross a river using a boat which can hold two people (maximum,) subject to the constraint that no woman can be in the presence of another man unless her husband is also present.
• Missionaries & Cannibals River Crossing: Three missionaries and three cannibals must cross a river, subject to the constraint that at any time when both missionaries and cannibals are standing on either bank, the cannibals on that bank may not outnumber the missionaries.
• Bridge Crossing: Four people approach a narrow bridge crossing a river at night, but it can only hold two people at a time. They have one torch between them, and because it’s dark, the torch must be used to cross the bridge safely. Each of the four people (A, B, C and D) travel at different speeds – 1, 2, 5 and 8 minutes respectively. When two people travel together, they must move at the slower person’s pace. Can all four people cross the river in 15 minutes or less? Click here for solution.
• Take a look at Magic Shoes to challenge your group with a physically-demanding traversing dilemma.
• Take a look at T-Puzzle to explore another team-based puzzle that comes with only one solution.

You’ve all heard the term ‘two steps forward and one step back.’ You’ll do well to remember this philosophy in our next exercise…

Coupled with one or more reflection strategies, here are some sample questions you could use to process your group’s experience after playing this simple problem-solving team puzzle:

• Was this puzzle easy or difficult for your group to solve?
• What type of thinking was necessary to solve this problem?
• Were there any breakthroughs in your thinking? What was an example?
• How might this thinking apply to other areas of our group’s life?