# Penny Queueing Exercise – Lean Process

This simple simulation exercise helps people to understand the efficiency that can come from moving away from a waterfall or large batch process. The exercise can be done with 20 pennies, 5 people and a clock with a second hand.

The exercise simulates processing work in the form of flipping pennies from heads to tails and back. Four people in the Team sit at a table or other hard surface in a line beside each other. The surface must allow for easily sliding the pennies. The fifth person, the Manager, starts the process and times it. The Team will process the pennies twice…

First Pass – Waterfall Large Batch
1. The Manager gives all the pennies to the first person in the Team and notes the start time. The pennies should be in a big jumble.
2. The first Team member chooses a side (heads or tails) and flips all the pennies onto that side.
3. The person with the pennies passes the whole pile of pennies to the next person. That person then flips all the pennies to the other side.
4. Repeat step three until the last person on the Team has flipped them.
5. The manager notes how long this took.

Second Pass – Waterfall Small Batch
1. The Manager gives all the pennies to the first person in the Team and notes the start time. The pennies should be in a big jumble.
2. The first Team member chooses a side (heads or tails) and flips all the pennies onto that side. As each penny is flipped, the Team member passes it along to the next person.
3. Each person flips their pennies as quickly as possible and immediately passes them on to next person.
4. Do this until they are all flipped.
5. The manager notes how long it took for the first penny to go through all four Team members, and how long it took for all of them to finish.

Optional Third Pass – Parallel Small Batch
1. All the pennies are in a random jumble in the middle of the table.
2. One Team member calls heads or tails and the manager notes the start time.
3. Each person grabs a penny at a time from the pile.
4. All working at the same time as quickly as possible, each person flips the pennies first so they are all the same as the original call if needed, and then three more times
5. As each penny is finished 3 or 4 flips (as appropriate) it is pushed into a separate done pile in the middle of the table.
6. The Manager records the time for the first penny to be put into the done pile and for all of them to be completed.

I heard of this exercise through the agile coaching grapevine, originally from one of my apprentice coaches. After attempting to trace it back to its origins, I believe that it may originate in some lean training, but I am uncertain at this time. I have made my own modifications to the original exercise and these are reflected above. If I am able to properly acknowledge the origin of this exercise, I will update this entry to do so.

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