After lunch was eaten and babe farewelled, I cleared the table for the Big Bridge Shape Testing. The moment was slightly underwhelming; Yoshi informed me he'd seen this done on Backyard Science and he knew which shape would be stronger already. I strongly encouraged him to test his hypothesis anyway.
So here is Yoshi testing the simplest bridge shape. It held the grand total of two Lego blocks before collapsing. "I knew it would do that." said Yoshi.
We tried an arch, a combination of arch and flat - better, but still prone to collapse.
This was more like it! An accordion layer or two, sandwiched between two sheets of paper, for a grand total of 50 plus Lego blocks! Exactly as Backyard Science had predicted :) Ah well, it's good to have hands-on experience.
We read some of the info in our Bridges book, but to tell you the truth, Yoshi wasn't mad keen on that bit of the afternoon. Hmm. Have to work on that.
We did use a picture of a bridge to build a model showing different parts - span, supports, abuttments, lead-up. The building blocks were still downstairs courtesy of tower building baby, so we just used those.
And then we called it an afternoon. I had many more pictures to show you, but Blogger is being temperamental and in any case, one arch bridge looks much like another :)
I am so looking forward to making concrete next Friday! A trip to the op-shop is needed before that, to buy an old saucepan I don't mind spoiling with sand and cornstarch. Join us then and see how it goes.