the penny game is a easy to play lean game that shows the benefits of creating flow and reducing waste. And the best thing is, you only need 100 pennies or cents. Furthermore the length of the game is quite short, which makes it possible to illustrate the benefits of flow in a short period of time. Depending of the size of the group you can do it in 15 to 25 minutes.
The penny game is already a long time around in the lean community. Therefore it is hard to find its origin. Many people have modified the game to fit their needs. Hereunder you find the version I use.
- one or more groups from 3 to 5 persons
- 100 pennies or cents per group
- a clock or stopwatch to time the different rounds
- each participant has to turn all pennies or cents and pass them to the next person.
The turning over represents added-value steps in an actual process. Depending on your process you could give each person a role. For example for software development you could use the roles: Designer, Developer, Tester. Or for a production process you could use the roles. Cutting, Drilling, Assembly.
Don't forget to include a customer! This role can be played by the facilitator. Or by a participants in larger groups.
round 1: Batch production
In round 1 the coins are passed in a batch to the next person. The batch size is 20. This means the first person has to turn over 20 pennies before sliding them over the table to the next person.
The customer times how long it takes to get the first batch and the last batch.
If you would like to add the quality aspect you can count how many are heads at the customer. Tails are defectives. Don't tell the participants this yet! Let them know only after the first round. Make sure that when you supply the pennies to the first participant you lay them on the table so that you will have some tails at the end of the round!
After the first round ask the participants to improve the delivery time of the first penny to the customer. And tell them to make certain that they do not deliver any defectives (in other words no tails at the customer).
round 2, 3, 4 ....
There are may ways to play the next rounds. One way is to give them targets:
- round 2: eliminate defects (tails at the customer)
- round 3: go for a batch size of 5
- round 4: go for one piece flow
- round 5: minimize transport (transport : sliding of coins on the table)
Another way of playing the next rounds is to give them complete freedom to improve.
You can play as many rounds as you want. You can play every time a new round as long as there are ideas to improve further after the previous round has ended.
Typical improvements are:
- Ask the first person to make sure all the pennies are laying currently so that the customer will only get heads
- Ask the supplier (= facilitator) to make sure all the pennies are laying correctly so that the customer will only get heads
- Work with smaller batches
- Work with one piece at the time
- Moving the pennies from hand to hand instead of sliding
- Putting the pennies on a central place on the table with the participants around them
Don't forget to measure the delivery time for the first and last penny to the customer!
The line balancing extension
if you want to include line balancing in your penny game you will have to create first some unbalance in the cycle times between the different operators. This can be done as following:
- Give the first participants the pennies is a small bag. The participants has to take out the pennies first and lay them on the table before the turning over can start.
- Give one of the other participants the extra rule that he or she can only use the left hand (assuming that the person is right-handed). This could for example simulate the use of an older not so efficient machine. Or a production step that takes longer.
You will have to measure the cycle time of each participant. this can be done by the facilitator or you can create a team leader role for each group. This participant will not turn pennies. But will measure all the different cycle times and delivery times.
For the next round you have to turn over the pennies as many time as there are participants (excluding the team leader). You need to do all the added-value steps in order to have a happy customer. Who does this is however free to choose. A solution where participants 1 takes out the pennies from the bag, the participant which use the left hand does one turn and the participant which can use his right hand does 2 turns is acceptable (3 participants, 3 turns).
The variation extension
Most customer do not want 1 product. but a Variation of products. One way to incorporate this variation into your simulation is to work with 1 and 5 cents. The customer will create an order which consist out of 1 cent's and 5 cent's. Per Order he can ask between zero to ten 1 cent's and between zero to three 5 cent's. The customer has to order at least 1 coin. The customer order is given to the team leader.
You will need to have hundred 1 cent pennies and thirty 5 cent's. There will be 10 rounds. You can let the customer decide freely what he will order or you can give him a sequence. This is the sequence I like to start with:
- 5 x 1 cent + 2 x 5 cent
- 10 x 1 cent + 0 x 5 cent
- 4 x 1 cent + 3 x 5 cent
- 8 x 1 cent + 3 x 5 cent
- 10 x 1 cent + 3 x 5 cent
- 0 x 1 cent + 1 x 5 cent
- 8 x 1 cent + 3 x 5 cent
- 6 x 1 cent + 1 x 5 cent
- 10 x 1 cent + 3 x 5 cent
- 6 x 1 cent + 2 x 5 cent
The sequence is not given in advance to the team.
The team leader has to make certain that the customer get's what he wants. The rules for round 1 remain the same except for the batch size. The batch size will be 10. This can be a batch of 1 cents or a batch of 5 cents. The team leader decided what has to be produced.
It is normal that there will be a stock at the end of the line. The team leader will "deliver" the order to the customer. The team leader can slide the requested coins in an area which is designated as the customer delivery quay.
In the next rounds you can explore smaller batch sizes, one piece flow and kanban.
There are several learning points which can be taken away from this simulation:
- The link between batch size and lead time will become clear. Products are delivered quicker when smaller batches or one piece flow is used.
- The work in progress is reduced when using smaller batch sizes or one piece flow. This reduces the cost when there is a drop in demand or warranty issues where all products in stock have to be scrapped or reworked. Also working with small batches reduces the impact when there is a customer change.
- Some of the 7+1 wastes can be identified and eliminates or reduced. Waste such as transport (sliding the coins over the table), waiting (on the previous participant to be ready), overproduction, inventory can be identified and reduced.
- Introducing Kanban/Supermarkets will limited the work in progress (WIP) and free up capital. It also helps you to deal with variations in the process.
- A pull system give you lower WIP compared to a push system
- Line balancing increase the output and spreads the burden equally over the team (Mura).
- By introducing the 5 lean principles you will reduce waste and increase profit
Have fun playing this game!