Exercise: Estimate Number of times you can Fold a Paper in Half

An Exercise in Estimation: How many times can you fold a piece of paper in half & half again...

I do this exercise when beginning scrum teams start story estimation or task estimation. While this exercise has a unique twist that is very different than task estimation or story estimation - very few people foresee this aspect of the exercise, so it adds to the ah-ha moment.

Start by giving everyone a sheet of typical paper (8.5 x 11 in the USA - although the size just doesn't matter). Then tell them the exercise but ask that no one do any thing yet. First we will estimate. The task is to estimate how many times you could fold the paper in half and then again in half and repeat... without doing it what's your estimate of the number of folds?

Ask people to call out their estimate, write then on a board in no particular order or fashion.

Typical groups come up with estimate in the range of 5 - 20 folds.

If you want to do math... calculate an average estimate... or just circle the mean value.

Next have the group fold the paper in half and half again up to 4 times - then STOP and estimate again. Same as last time - call out the estimates and write them down on the board.

Next - fold the paper until you are done. How many folds did you get?

Now the debrief: What did you learn in this exercise? What happened to the estimates - why did this happen? What generalizations of estimating can we learn from this example? So when do we practice this re-estimation technique in Scrum?

For BONUS points - how many times do you need to fold paper to get to the Moon?