Oh dear - remember what I 'promised' about materials?

Danah raced over to where I was sitting this morning when she arrived at school.  In her hand she was clutching something.  Obviously something pretty exciting.

"Look!" she exclaimed all-in-a-rush.  "I've got something.  It's glass."

Ooh-er, thought I.  Glass?  Not good!  Open up Danah.

But, on closer inspection, while it was glass, I was not overly worried.  You see, there was something different about this glass.  Let's see if we can remember what.

Once we had all had the chance to look at it, we agreed we had seen something similar before (and had in fact written about it in an earlier post, no less!) Yes, it was glass.  But where did the glass come from?  It had been broken, but instead of dangerous shards, it had formed into chunks, or cubes with no really sharp edges. 

We asked Danah where she found it.  "I found it when I got out of the car.  It was in the parking place."

That got a few 'sharp' minds whirling.  Justin began by trying to explain.  "It's from a car when you open the window."

Fiona clarified.  "I think it's from the broken window of a car."

Then Joe remembered what it is that is special about glass in cars.  "It is laminated," he said.  "Laminated means that there is a layer of plastic on the glass (actually there is usually one layer of plastic in between two pieces of glass) which means that it doesn't break into sharp pieces; the plastic holds the glass together and that makes it safe."  The glass is also toughened which means that if there are any pieces, they are just the relatively harmless chunks that Danah found. 

So mystery solved!  However, there is still the mystery of how a car windscreen got broken in the school car park.....