8 Monkeys in a Cage – a Mura Learning Game


Last time when I was teaching Lean, I found myself in trouble. The topic was to teach students about 3M principles: Muri, Mura and Muda. As always, I planned to do some practical learning games. There are a lot of games about Muda, some very good about Muri, but very few about Mura. Additionally, we were in a very small classroom with computers fixed at desks, so I was in trouble finding some good Mura learning game appropriate for my situation.

So, I created my own Mura learning game which requires only a projector, a piece of paper and a pen. Even a projector is not really necessary if you print monkeys and give it to students. The game itself is improved through multiple sessions and it seems to me it is a solid Mura learning tool. That’s why I decided to publish it here and at tastycupcakes.org.

Here is a game description:


Mura is one of three fundamental Lean principles. In short, it’s about unnecessary variations. It states that people are more productive when not dealing with unnecessary variations. Playing this game should help people to feel a situation when variation is unproductive.


20 minutes


  • a projector and a presentation
  • 2 pieces of a blank A4 paper per student
  • a pencil for every student


Give two blank A4 papers to every participant. Ask participants to draw “cages” on their two papers, so that monkeys can move in later. Every side of both paper should be divided by two lines resulting with four equal squares on each side of both papers. After this, every participant should have a total of 16 cages ready.

Tell participants that in this game they are not competing each other and not competing against clock. The goal is to feel the difference and to discuss it at the end.

The Game

Put a slide 2 (the one with four different monkeys) at projector. Tell participants to draw these four monkeys in cages onto their paper. They should do it by drawing monkey no. 1 in a top left cage, monkey no.2 in a top right cage, monkey no. 3 in a bottom left cage and monkey no. 4 in a bottom right cage. After this they should turn the paper and repeat drawing of 4 monkeys. Give them 5 minutes for it.

Now, put a slide 3 (the one with only one monkey) at projector. Ask participants to take the second paper and fill in another 8 cages, but this time always with a same monkey. Give them 5 minutes for it.

The Learning Point

Ask some of participants how they felt during the first session (with different monkeys) and how they felt during a second session (with only one monkey). What was faster? Which session was more stressful?

After this, let them understand that a task was to draw 8 monkeys, not to draw 8 different monkeys. So it means these variations were unnecessary. Also, it is important to say that a real reason why they were faster during a second session was because they learned how to deal with this monkey.

Help participants to correlate this situation to a real world examples:

  • one of the worst situation are unnecessary variations in product backlog. It generates stress and makes us less self-confident during estimations. That’s why we need a balanced flow
  • it is relatively often that people implement multiple, slightly different implementations for a same problem. We don’t need such variations. In that case, we should use “a same monkey” – a component
  • ask participants to add more real world examples of unnecessary variations