Nim

In China, this game is known as jianshiji, which is translated to mean "pick up pebbles." This game was known in Europe as early as the 16th century. Some believe that the name "nim" comes from the German word nimm, which means "take." Did this game develop in both places because of its simplicity? Or did the concept travel from one place to another as global trade increased during the last 1,000 years? We will probably never know the answer to that question, but we do know how to play.

Questions

• Where did this game originate?
• What is strategy?
• Are games and math related?

Objectives/Skills

• Subtraction
• Deducing strategy

Time Required

45 minutes

Materials Required

At least 21 pebbles (or beans or buttons, etc.) for each child. The game starts with 12, but the number can grow.

The extension activity will require giving away 24-42 pebbles in a bag.

Procedure

• Pair up all the children in class.
• Each player has 12 pebbles. Ask the children to divide the pebbles into three piles of 3, 4, and 5 pebbles each.
• The two players in each game take turns picking up pebbles from one of their piles. 
• Each player must pick up and set aside one or two pebbles during each turn. The pebbles must come from the same pile.
• The winner picks up all his or her pebbles first.
• Let the children play the game several times. What is the best way to win? Teach children the word "strategy" means a plan for winning. There are strategies for all sorts of things in life: games, sports, careers, and even how one country relates to another country.
• If time and skill sets allow, try making the game more challenging with more pebbles and more piles. Does the same winning strategies work?  Why do strategies change sometimes?

Extension

Send the children home with a bag of pebbles. Ask them to teach a parent or guardian the game. The next day ask if they were able to play together. Did the parent or guardian understand the rules? Did the child explain strategy?