# Sphero Bridge Building

Every year, my 2nd grade GT students build bridges as part of a unit on Structures.  We have K’nex kits, and they enjoy learning about the different types of bridges as well as making their own versions.

This year I really wanted to have them do more than follow the instructions in a kit. When I saw the Sphero Bridge Building Challenge, I knew immediately what we were going to do.  I modified the lesson plans a bit, borrowing from some other bridge-building lessons I’ve seen, and created yesterday’s challenge.

I gave teams the task of building a bridge that would span a 14-inch gap between two table edges.  It would need to be strong enough to drive a Sphero across, and cost the least amount of “money” possible.

Of course, they didn’t have to spend real money.  I put a bunch of materials on one of my tables and gave them a chart listing the costs:

• Popsicle Sticks – \$100 ea.
• Straws – \$50 ea.
• String – \$20 per foot
• Paper – \$10 per sheet
• Tape – \$5 per 6 in. (the 1st 6 in. are free)

The students had to plan the materials they would use and then figure out the projected cost.  They had to sketch their bridges. Once I approved their plans, they could build.

I was so impressed with their planning!  They weighed the Sphero, used string to measure its circumference, did complicated calculations of the costs of materials, and measured straws and popsicle sticks with great care.  Great discussions ensued about the best designs for their bridges.  A lot of math was done – most of it correctly.

In the end, two groups succeeded in completing and testing their Sphero bridges.  Two did not.  Their reflections afterward were fun to read.  One student wrote, “We got our bridge done in time but we could have gotten it done earlyer if we had not been arguing.”   All of the students thought planning was essential to a successful project – except one, who stated, “planing wast of time.”  Another commented that the time it takes to complete building something can be delayed by things like, “how prodoctove your workers are.”  His teammate was more blunt, “Our bridge did not get finish because some people don’t work.”  They learned another reason for building delays can be when you don’t plan for enough materials and you have to wait for more to be delivered ( i.e. when there is a line of students waiting for Mrs. Eichholz to dole out more pieces of tape).

I will definitely add this to my lesson plans again next year.  It was one of those experiences where you find yourself slightly overwhelmed by the utter chaos but completely awed by the creativity and engagement of your students.  At the end of the activity you feel the contradictory, but welcome, combination of being both drained and energized.