Single Piece Flow

Try this sometime: Make a list of everything you are going to do in the next few weeks at home. Everything from dishes, laundry and other household chores, to fun things like going out to dinner or renting a movie, to larger endeavors like planting that garden or repainting the bedroom. Estimate how many days all this will take and write a date on the calendar to review the list to see if you got everything done.

Scrum teams often get to the end of a Sprint and have some work that isn’t done.  There just wasn’t enough time.  Do we move that into the next Sprint?  Do we put it back on the Product Backlog?  Do we re-estimate it?  Is it bad that we didn’t get everything done?  What if we got a lot of things 90% done, but nothing 100% done? 

Let’s say we have 4 PBI’s in a Sprint, and the team works on all of them and makes good progress, but doesn’t quite complete any of them.  We’re left with something that looks like this:


In this case, we’ve done a lot of work, but delivered zero value.  Nothing is DONE, we have nothing to show at the Sprint Review, and we have nothing to potentially ship to customers.  We also have to figure out what to do with this undone work now.  Carrying it over into the next Sprint is the most common approach.  There’s a huge downside here in that the PO no longer really has control over the order of the work, and therefore over the delivery of value.  By not getting to done, the development team is de facto controlling the order of the backlog.

Here’s a better idea.  Work each PBI to completion before starting the next one.  This is called “Single Piece Flow.”  Or if that seems silly given your team history or context (team size comes into play here often), then try just two at a time.  We might end up with something that looks more like this:


Now in this scenario, we got 3 of the 4  PBI’s all the way to DONE, delivered those valuable features, and then made just a bit of progress on the 4th PBI.  This is a much better, more agile, place to be.  You have 3 things to show at a Sprint Review, a much short discussion about what to do with the 4th PBI, and the PO is in control of the backlog and can decide what to work on in the next Sprint.

The biggest argument against working like this is typically: that’s not very efficient.  We might have idle time, or might have to pair-up when we could be working on separate things.  We can actually make more progress on work when we wplit it up in a way that allows us to each work 8 hours per day. 

Yeah, you are probably right.

But the economics here are really interesting.  Think for a moment in terms of time-value of money, depreciation of customer needs, the economic utility of having features done and useable now versus later, and the risk of developing the ‘wrong’ product.  In this context, it will always be more valuable to work one PBI at a time all the way to DONE.  Even if this is less efficient.             

So you sit down to review your to-do list with your family. You proudly announce that you washed the dishes but didn’t put them away, washed the laundry but never had a chance to move it to the dryer, rented a movie for the family to watch but never organized a night when you’d all be home, and repainted the bedroom and never got a chance to remove all the painters tape. Good job?


Sprint Review Technique: The Science Fair

Young Jimmy is in 3rd grade.  He's constructed an immaculate paper-mâché volcano.  It took every spare minute of the last to weeks to make.  His mom carefully loads it in the back of the minivan.  The anticipation is too much for Jimmy, he can't even look.  Arriving at school, Jimmy helps her carry it into the gymnasium, one step at a time, a balancing game like he's never experienced before.  Just as Jimmy gets his red and black peaked masterpiece setup in his booth at the Annual Science Fair, panic strikes him.  So wrapped up in the architecture and construction of the erupting mountaintop itself, he's forgotten the vinegar and baking soda at home.  "No worries," he thinks to himself, he took plenty of pictures during the test runs, "I'll just post the pictures up in my booth and the judges can see how absolutely perfect my volcano is."

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When you have many teams working on one product, having each team present and show their portion of the increment could take hours.  And some stakeholders are only interested in certain portions of the product, and feel as if their time is being wasted in long Sprint Reviews.  One technique that remedies this situation is the Science Fair or Bazaar.   I'm seeing and using these more and more for Sprint Reviews.  

The concept is simple.  The PO kicks off the Sprint Review with everyone's attention.  She might go over the product vision, roadmap, state of the marketplace, and highlight significant new features delivered in the last Sprint.  Then she dismisses the massive group and invites them to find teams they wish to talk with more in depth.  The teams are lined up on the outer edges of the room (or in separate meeting rooms, hallways, or any free space!), with their team name and core functionality area clearly marked with a sign.  They invite stakeholders into their "Science Fair Booth" and walk through the Increment with them, ask for feedback, allow the stakeholders to interact with the product, observe, and thank them as the move on. 

This technique is great of massively scaled projects with dozens of teams.  Everybody gets an overview of the entire product, but then all the details are left to individual teams.  Stakeholders can pick and choose what they want to see, and spend as little or as much time as they wish with the teams.  When starting out, I highly suggest that you coach teams to pull in stakeholders actively, just like merchants at a bazaar, coaxing them to come and interact with the product and give feedback.  As a new technique, sometime people just need a little nudge in the right direction.  Get excited for showing off your product, just like Jimmy.  Speaking of Jimmy....

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As Jimmy is putting the finished touches on his arrangement of photographs, he spots Susie setting up next to him.  Now Susie has always been just a bit behind Jimmy in school, always getting the second best marks, always finishing the race just behind Jimmy.  Her volcano is a solid specimen, certainly, but nothing compared to the pixel-perfect replica of Vesuvius that Jimmy made.  Susie, however, has remembered he vinegar and baking soda.  As the judges make their rounds, Susie carefully measures out the exact ratio of ingredients, sets up her volcano, and at just the right moment: SWOOSH! 

Guess who wins the blue ribbon? 

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Regardless of the Sprint Review format you choose, remember this: you have to actually show your done, working Increment of product.  You have to actually "pour the baking soda and vinegar together."  No pictures, no screenshots, no mockups, no prototypes, no talking endlessly.  Show your work.  This is your chance to show what you've built.  This is what builds trust with stakeholders, and allows you to collaboratively inspect the product, and adapt for the next Sprint.  Luckily, product development isn't as messy as paper-mâché.  Well, rarely.