Monday, June 20, 2016

Homeschool STEM: Build a Popsicle Stick Truss Bridge

No work plans this week! The kids are day camping, which means that I have five full days to mark off every single thing on my to-do list--you know, the one that I last caught up on last year when the kids were at camp.

I always think that while the kids are gone, I'm going to take an entire day and just drink coffee and watch movies and read, but I don't. The temptation to do ALL THE PRODUCTIVE THINGS is far too great.

Anyway, before I do my first mile on the treadmill and read some of my Abraham Lincoln biography over breakfast and work on my freelance assignment (craft projects that you can do instead of setting off fireworks with kids--tough one, right?) and paint the frame to the magnetic memo board and see if my repair to the bread machine is functional and... well, I'm boring you just telling you about my productive day.

tl;dr: Before I get to the rest of my day, let me tell you all about how awesome truss bridges made with popsicle sticks are!

A truss bridge can be a cost-effective way to span a distance, because those cross-beams provide a LOT of support for their size. And once you've discovered the genius of the triangle, you'll find yourself using it in all sorts of designs, not just bridges, to increase stability. On our day trip to the Indiana State Museum a few months ago, I discovered that my K'nex pyramid was undefeatable at the earthquake table--all the other little kids with their non-pyramid K'nex structures were so jelly!

To explore truss bridges, the kids and I built models as illustrated in this tutorial. Syd and I built one bridge, and Will built her own, slightly simpler, model:


Again, although it would be more accurate to distribute the load for the weight testing across more of the bridge's deck, testing this way still gives you a good basis for comparing the different bridge types, which is all that we need:



You can see that this simple bridge took a pretty good amount of weight before it went down! If you were super careful with your construction techniques, made each component of your bridge as accurately as possible, and tested it in a controlled environment, it would stand up to a LOT more stress before buckling.

For bonus points, compare your truss bridge to a beam bridge and a suspension bridge!

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