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"Palmagatchi"   (Summer 2005)



Big Fish - Little Fish Game Instructions

Playing the Game

Players in this game are either a school of big fish or little fish. Big fish need to eat little fish to survive and little fish need to avoid big fish to survive. The interface is very simple. After entering your name on the starting screen (see the general instructions page), wait for the whole group to be ready to start. You will note on the starting screen that you are told whether you are a big fish or a little fish, both in words and with a picture. When the game begins the screen will tell you how many fish are in your school. If you are a big fish you will have an Eat button that you use to eat schools of little fish. Both big fish and little fish have graphs of their population size over time, and a data button that they can use to look in more detail at their populations.

Schools of big fish decline over time unless they eat little fish. Schools of little fish increase over time unless they get eaten by big fish. You can play additional rounds of the game by going to the menu in the upper left, and click on restart game.  It will kick you back out to the name screen with your name already filled in.  Everyone should start the second round together. You cannot play with other players if you restart your game while other people are playing the first game, your machine will not communicate with theirs. You can also stop the game at the end of a round to preserve your data until the next round.


Game Parameters

The most important parameter to set in this game is Big Fish and Little Fish. You can tinker with the right ratio, but usually making a 1:1 ratio or a 2:1 ratio (little fish to big fish) works well. The other parameters that you can change are how fast the big and little fish schools decline/increase and how many little fish are converted to a single big fish when they eat.

A complete explanation of the parameters is given here:

  • Big Fish / Little Fish - determines if the player is a big or little fish
  • Seconds Per Tick
    • Big Fish - how many seconds between decreases in schools size
    • Little Fish - how many seconds between increases in schools size
  • Population Rate
    • Big (Decay) - the percentage that the big fish decrease each tick
    • Little (Growth) - the percentage that the little fish increase each tick
  • Little/Big Fish Ratio - determines how many little fish need to be eaten to make a big fish
  • Game mode - which round the game is in

Information for Instructors

This game is a lot more about the strategies that they players create than the technology itself. We usually don't give the players any of the quantitative information at the beginning, but the challenge of how to balance the pond with this info is still difficult.

People should wear red/green nametags if possible and turn them to red if they are big fish and green if they are little fish (and take the tags off when they are dead). 

When playing the game we usually have the first round simply be whatever the players like. Little fish usually try to hide or run, or sometimes the blend in with big fish or dead fish. But what quickly happens is the big fish deplete their little fish stock and quickly die out themselves. After the first round we ask, "What Happened?" Then do some probing and ask some more directed questions towards the whole pond dynamics.

We engineer a second round with a slightly different context - how can we keep the as many fish alive in the pond as possible and maintain the biodiversity (both big and little fish). As a group players will then brainstorm strategies for keeping big and little fish alive - cutoffs for feeding, spatial arrangements, signals, etc. Sometimes this requires a couple of rounds to do well.

Note that students can see their individual data, but there is currently no automatic way to pool data. It can be effective to have students copy their numerical data into a spreadsheet and then combine the spreadsheets to see the whole class data.

Discussion at the end can center on predator-prey dynamics, overfishing, biodiversity, evolution, and behavior among other topics.



MIT Teacher Education Program