Tag Archives: Logic Puzzles
This week’s puzzle has been around for many years. It is one of a family of puzzles which have varying degrees of difficulty. These puzzles usually have three common characteristics. First, they all involve getting something across a river (or pond) in a boat. Second, one or more of the things in each puzzle is in danger of being eaten if the puzzle-solver is not careful. Lastly, the puzzles are intended to be done as thought problems without any manipulatives.
By modifying this last characteristic, and allowing manipulatives to be used, many of these puzzles can be done by elementary students. I have used the puzzle presented here quite successfully with students from second grade up.
In The Frustrated Farmer, a farmer must transport a fox, a chicken, and bag of corn across a river in a row boat. She can only take one thing at a time. If the fox is left alone with the chicken (on either side of the river), it will eat the chicken. Likewise, if the chicken is left alone with the bag of corn, it will eat the corn. To solve this puzzle, you must find a way for the farmer to get the fox, the chicken, and the bag of corn safely across the river.
To make this puzzle easier for students to solve, we have included pictures of the farmer, fox, chicken, and bag of corn. We suggest that these be laminated and each one taped to a pencil or piece of dowel. A scrap piece of lumber can be made into a boat by sawing a point on one end and drilling two holes (the same diameter as the dowels or pencils) for the passengers. The river is made by cutting a piece of butcher paper in the shape of a meander. The river is glued to a piece of green butcher paper which forms the two banks.
When students have successfully solved the puzzle, they should record their solution in words and/or pictures.
In this puzzle you must help a farmer get a fox, a chicken, and a bag of corn safely across a river in a boat. The farmer may only take one thing at a time in the boat. She cannot leave the fox and the chicken together on either side of the river, or the fox will eat the chicken. Likewise, she cannot leave the chicken alone with the bag of corn or the chicken will eat the corn. How can the farmer get everything across the river without anything being eaten?
Click the arrow below to view the solution.
In The Frustrated Farmer, a farmer needs to find a way to transport a fox, a chicken, and a bag of corn across a river in a boat. She could only take one thing at a time. If the fox was left alone with the chicken (on either side of the river), it would eat the chicken. Likewise, if the chicken was left alone with the bag of corn, it would eat the corn. To solve the puzzle, you were to find a way for the farmer to get the fox, the chicken, and the bag of corn safely across the river.
One possible solution to this puzzle follows. The farmer first takes the chicken across the river and leaves it on the other side. She then comes back and picks up the fox and takes it to the other side. When she gets there, she drops off the fox and brings the chicken back with her. She then drops the chicken off and picks up the bag of corn which she takes across the river. Finally, she goes back and picks up the chicken and takes it across the river one last time. When this is done, she has safely transported everything across the river and is able to go on her way.
I just started reading Fractions in Realistic Mathematics Education by Leen Streefland, and there, on page 5, Streefland gives as an example an old puzzle problem that I remember giving my students more than 40 years ago. “An old Arab, Anwar his name, decreed before he died that his eldest son inherit one-half, his second… Continue Reading