Tag Archives: bridges

More Bridges

My 2nd graders study structures, and our 2nd semester is spent on man-made structures.  We start with bridges, and I usually challenge the students to make bridges out of different types of materials.  Even though the activities always seem to engage them, I felt like I wasn’t quite making the lessons meaningful.

This year, I started simple by showing the students a BrainPop video about bridges and using our Depth and Complexity mats to discuss the video.  This week, we reviewed a lot of the Language of the Discipline (they particularly like the word, “abutment,” – for obvious reasons), and they remembered quite a few from the video.  Then I challenged them to do this activity.  The students were good at connecting that their attempts at paper bridges were beam bridges, but they were definitely getting frustrated after about 10 minutes of trying and failing.


At this point, I would usually have shown them the solution on the teacher notes.  But this time I asked them to pause while we looked at the shapes interactive on the Building Big site.  After the students realized that triangles are the strongest shape, I asked them to apply that knowledge to some new attempts at the paper bridge challenge.  I was surprised to see some of the creative options they developed.

I finally did show them the solution on the teacher guide, and they were quick to understand and explain why the change in the paper’s shape made it suddenly stronger, Then they came up with variations and improvements.

This was the first time I really felt like the students weren’t just having fun building bridges, but were actually stepping through learning while developing innovative ideas at the same time.  They were explaining how the shapes they tried changed the force on the bridge, as well as how placing the load could affect the outcome.

As I watch many people on Twitter share “STEM” building challenges, I wonder how many, like my first attempts at bridge building lessons, might be more fun than educational.  Though fun is great, I feel better now that the students have found a way to make a “bridge” between their enjoyment and their learning.

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.



from "Bridge Constructor Playground Free"
from “Bridge Constructor Playground Free”

My second grade gifted and talented students are currently studying bridges.  We have been using the PBS Building Big site, which has some great interactive labs and suggested classroom activities.  We have also been using the K’Nex Bridges kits, and will be exploring the “Bridge that Gap” challenge (Here are some other K’Nex Challenges).  There is also a Structures Curriculum packet that is a free download from K’Nex.  Here you can find a great compilation of famous bridges. One of my favorite new resources, though, is a pair of iPad apps that allow the students to learn about different materials and types of bridges by making their own and testing them.  They are very similar.  One is called, “Bridge Constructor Playground.”  This one gives a tutorial that slowly introduces the different types of materials and methods.  Users can build virtual bridges and test them with cars and trucks.  What I like about this app is that you can have many different answers for each phase.  What I don’t like about the free version is that it has an advertisement between each level.  (The kids quickly learned to hit the “x” every time, though. ) The other app is merely called, “Bridge Constructor.”  In this one, you are given different scenarios and budgets for your designs, and must stay within those constraints to meet the challenge.  There is a free version of this app, as well, and it did not appear to have as many ads as the “Playground” version did.

We are going to add some depth and complexity to our lesson by talking about multiple perspectives and the ethics of building bridges.  The 2nd graders truly seem to be enjoying this portion of our “Structures” unit, and we may have a hard time moving on!