The girls came home from signing up for the summer reading program, and announced they had to build bridges. Silly me, I thought they'd need to read books, and was caught off guard. Well, a little off guard, I knew the library had a science theme going this summer, and it's not like we've never built a bridge before.
I sent the girls in to watch
The Magic School Bus Under Construction, and then sat back to see what they would come up with on their own. The younger girls (ages 8 and 9) opted for a toothpick and marshmallow construction.
They used triangles for extra strength in their design. They learned quickly, that the squishy marshmallows allowed the toothpicks to move, and come apart. A problem they attempted to solve by reinforcing the connections with clear tape - a lot of clear tape - nearly an entire roll of tape.
Then, they discovered another problem. They had wanted to test their bridge with a couple of Lego cars, but they had forgotten to allow a high enough clearance on their bridge.
Finally, they decided to test the bridge with a Hot Wheel. The bridge held, but even with the tape, was not very stable. We all agreed it was not the sort of bridge we'd want to be stuck on in a traffic jam, but it might do for a quick river crossing in an emergency.
A (age 13) had some sort of suspension bridge in mind, but decided it was too much work, and modified it to a simple rope bridge, along the way. She used Dixie cups with toothpicks stuck in the top...
...to support straw pieces tied with dental floss ropes...
...with a straw "bar" threaded between them. There was no pulley system, so the Lego man would have to lean across the bar, and pull himself down the ropes by hand.
While the girls were busy engineering, I did a little Googling, and found a simple craft stick bridge idea from Nicola at
My Little Explorer, for us to try together. Nicola's bridge was made by gluing jumbo craft sticks to parallel strips of ribbon.
We opted for masking tape...
...under...
...and over our craft sticks...
...keeping them secure, and covering the sticky side of the loose ends of tape, so they could be used like ribbons...
...for tying up both ends of the bridge. The bridge was sturdy, but without side rails, would be risky on a windy day. It gave me flashbacks of crossing the
Royal Gorge Bridge as a child, except that one has side rails.
What do you think? If you were a Lego man which bridge would you choose to cross?