Tuesday, April 13, 2010

"Build a tower" and other design challenges

Last week, I had the opportunity to attend a couple of workshops held by Chris Rogers at ACEC2010. Chris Rogers is an engineering education guru who will be guiding my study and research at Tufts later this year.

I enjoyed the various design challenges that Chris gave us in the workshops. Across the two 2-hour workshops, the challenges included...
  • In pairs, build the tallest tower that you can using the small bag of technic/NXT LEGO pieces provided. You have 5 minutes, and you may only use your non-dominant hand!
  • In pairs, build a robot that can move forward, but wheels can't be use as wheels (most teams didn't have any wheels). Time: 1 hour. The NXT must either be part of the robot, or dragged along the ground. (I.e. the NXT brick can't be carried by a human following along)
  • Individually (and without looking at anyone else's work!), you have 3 minutes to build a duck from six LEGO pieces: two red 2x3 red plates, two 2x2 yellow bricks, one 2x4 yellow brick, and one 1x2 yellow brick.
  • In pairs, build a structure using all your pieces that stays together when it is pushed off the table... without any talking! (you can, however, use pencil/paper or any other non-verbal communcation.) Time: 5 minutes.
  • In pairs, build a structure to hold the NXT brick off the table surface... using only one hand.
  • In pairs, create an arm that can detect and move giant smartie chocolates into different position based on their colour.
The themes that emerged from these challenges related to engineering design and included:
  • the importance of goal clarification
  • understanding the client's needs
  • design limitations/constraints
  • multiple (and varied) solutions to single goal

Tower building in my robotics class
I was keen to try some with my own students as soon as possible, so I gave my students the tower building challenge. I didn't have separate bags of pieces ready to go, so instead...
  • I asked each student to go to the parts cupboard and select any 10 non-electronic pieces they liked. At this stage they had no idea what the challenge would be, so I suggested that take a range of pieces, eg. include beams, axles, connectors, etc.
  • Back in the room, I put them into groups of three (pairs would've been fine too), including people they wouldn't normally work with.
  • I gave them 5 minutes to build the tallest tower they could out of their combined pieces, using only their non-dominant hands.
  • We compared the models, and noted that some were more stable than others. Conveniently (from a teaching point of view), the tallest towers fell over when their tables were shoved, but the shortest towerdidn't. We discussed why this might be the case, and one of the students suggested the the centre of gravity might have something to do with the stability.
  • I gave them two minutes to discuss their strategies and exchange any of their parts for parts from the cupboard, on a 2 for 1 basis (ie. for each piece they take, they have to return two pieces).
  • They then had five more minutes to rebuild their tower, and we compared the results.
  • In the end, the tallest tower was also the most stable. It was also from the team that traded the most pieces. It had three large, thin wheels as the base, and the height came simply from axles and straight axle connectors. It provided a striking example of a low centre of gravity, and was a great way to finish the activity.

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