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Recursive Water Balloon Drop: A Design Process Exercise

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2015 ASEE Annual Conference & Exposition


Seattle, Washington

Publication Date

June 14, 2015

Start Date

June 14, 2015

End Date

June 17, 2015





Conference Session

Design in Engineering Education Division Poster Session

Tagged Division

Design in Engineering Education

Page Count


Page Numbers

26.1318.1 - 26.1318.11



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Paper Authors


Nathan Delson University of California, San Diego

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Nathan Delson, Ph.D., is a Teaching Professor at the University of California at San Diego. His interests include robotics, biomedical devices, product design, and engineering education. He is co-founder of Coactive Drive Corporation, a company that provides force feedback solutions. Since 1999 he has taught engineering design and been the director of the Mechanical Engineering Design Center at UC San Diego. In fall 2012, Dr. Delson introduced a Product Design & Entrepreneurship course, where students develop their own product concepts.

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Recursive Water Balloon Drop: A Design Process Exercise    Short-­‐term  classroom  exercises  can  be  an  effective  way  of  teaching  key  elements  of  the  design  process  before  students  embark  on  a  longer-­‐term  design  project.  However,  care  must  be  taken  that  the  exercises  teach  students  effective  design  process  methods.    An  exercise  was  developed  to  improve  upon  a  popular  egg  drop  exercise,  where  students  build  a  packaging  container  to  protect  a  raw  egg  and  then  see  which  design  can  be  dropped  from  the  highest  height  without  the  egg  breaking.  One  limitation  of  the  egg  drop  exercise  is  that  it  does  not  allow  for  design  iterations,  since  students  are  typically  provided  with  just  one  egg.  Another  limitation  is  that  there  are  no  readily  available  measurement  tools  to  determine  why  some  designs  work  better  than  others.    The  “Recursive  Water  Balloon  Drop”  exercise  was  developed  to  teach  students  how  to  manage  an  iterative  design  process  and  use  analytical  tools  to  improve  the  design  during  each  iteration.  Other  aspects  covered  included  creativity,  teamwork,  and  communication.  In  this  exercise  each  team  of  students  is  provided  with  water  balloons  that  have  been  filled  with  the  same  amount  of  water.  Each  team  developed  design  concepts  for  their  packaging  and  hypotheses  as  to  what  will  cause  the  balloon  to  break.  The  students  then  dropped  their  packages  at  increasing  height  until  the  balloon  bursts.  During  each  drop  the  event  was  recorded  with  a  high  speed  camera.  We  used  a  Casio  EX  that  could  shoot  at  1200  frames  per  second  (fps),  but  with  incorporation  of  high  speed  photography  into  iPhone  6  cameras  that  can  shoot  at  240  fps,  the  use  of  high  speed  photography  for  classroom  exercises  is  becoming  increasing  accessible.  Students  evaluated  their  video  footage  and  used  the  results  to  improve  their  design  in  the  next  iteration.    23  students  in  6  teams  of  students  completed  the  recursive  water  balloon  drop.  The  exercise  took  3  hours  of  classroom  time,  with  an  additional  oral  presentation  of  each  team’s  design  process.  Each  student  also  wrote  a  reflection  on  what  they  learned  during  the  exercise.  During  the  remainder  of  the  class,  each  team  competed  a  much  larger  design  project.  At  the  end  of  class  a  survey  was  administered  which  asked  how  the  water  balloon  exercise  impacted  effectiveness  in  the  larger  course  project.  The  largest  impact  was  in  increasing  effectiveness  in  the  Design  Process  with  57%  indicating  a  significant  help,  and  an  additional  23%  indicated  is  as  somewhat  helpful.  Increased  Teamwork  effectiveness  was  rated  by  52%  as  significant  and  39%  as  somewhat  significant.  Increase  in  Creativity  was  rated  by  39%  as  significant  and  44%  as  somewhat  significant.  Increase  in  Applying  Physics  was  rated  by  26%  was  significant  and  30%  as  somewhat  significant    A  new  exercise  is  presented  with  a  number  of  advantages  over  the  traditional  egg  drop  exercise.  The  exercise  included  use  of  iteration  and  high  speed  photography  for  analysis.  Student  survey  results  that  the  exercise  had  significant  value  in  preparing  the  students  for  a  more  in-­‐depth  deign  project.  

Delson, N. (2015, June), Recursive Water Balloon Drop: A Design Process Exercise Paper presented at 2015 ASEE Annual Conference & Exposition, Seattle, Washington. 10.18260/p.24655

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