Wednesday, April 11, 2012

Reach for the Sky

Today the 5th graders built skyscrapers.  I found this fun activity in the website, in an activity called Newpaper Skyscrapers.  It is accompanied by class material, but I found that material a bit lacking, but it does have great links to other web sites.  One link I used was "Building it Big" on the PBS site.  It is a great help for learning more about skyscrapers and a good overview of some of the ideas behind the building of them.  On this site they talk about geometry, loading and have photographs of some of the most famous skyscrapers.  There is also a great site called which has some great illustrations of big buildings all over the world and their height.  The PBS special did not have the Burj Khalifa in it, since the program predated its construction, so I got most of my information about the world's tallest building from its web site and from the skyscraper page.  The Burj Khalifa, by the way, is more than 2 times the height of the Empire State Building.

First, I gave a short overview of the history of skyscrapers, and a brief introduction on how they stand and how they withstand wind loads.  The major types that I covered, as shown in the teachengineering page were stone towers (B.C. onward), Gothic Cathedrals (1200's to 1600's) especially noting Notre Dame Cathedral and the flying buttresses (which of course was thought to be a hilarious term by the fifth graders and elicited giggles every time I used the term buttress), the Home Insurance Building (1880's), the Empire State Building (1930's), the Sears Building (1970'), and the Burj Khalifa (2011).  Each had a concept to get across.  The towers illustrated stout stone walls bigger at the bottom than at the top.  With Notre Dame I discussed the flying buttresses which held up the walls from the outside so they would not be pushed out from the weight of the ceiling.  I showed the idea of the reinforced supporting core for the Empire State Building, which is also a three dimensional grid of steel beams.  With the Sears Building I showed them the hollow tubes that surround the perimeter to provide support, and finally with the Burj Khalifa we discussed the reinforced center support supplemented by the idea of buttressing.

Next, I gave them 4 sheets of newsprint and 12 inches of tape and let them work on building their skyscrapers.  They were to build a skyscraper that could stand on its own without being taped to the table, and then withstand a wind load: a big breath blown on the tower from an arm's length away.

It is fascinating to watch how the students work together, or not, and how their minds think.  I worked with 5 classes today.  In the first three classes, not one group used the cone.  In the fourth class, several groups used a cone, but that may be because my son saw one of my designs that I quickly made just to test out the exercise.  My design used succeedingly smaller cones to attain height and stability.  However, I only obtained 28 inches of height in my quick design.  Another interesting thing to note was that the students tended to put the smaller tube inside the larger tube and then taped it to the larger outer tube.  None of the students stacked cylinders so that they were supported by the one below rather than just the tape.

The most successful designs used flying buttresses that the students made of rolled up paper and attached to a paper base.  The flying buttress designs reached heights of 32" and 50".

The most successful design of the day was a tripod design which attained a height of 50 1/2 inches.  This design had the most stability of any of the designs.  It used three rolled up cylinders which fit in the base of another cylinder to achieve its height, a very elegant design by the students!

All of the students had a great time, and wanted to stay and work on their designs longer than the allowed time.  That for me is a success, along with the fact that they did learn a few things today.

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