This process is always harder than I think it wil be.
With Ditch Diggers, I was bobbing up and down on an inner tube in Kauai as a tour guide told us that two groups dug these irrigation tunnels by blasting and digging their way towards each other from opposite ends.
With Bubble Wrap, I was reading about an Italian performance artist who passed out sheets of bubble wrap of different sizes so people waiting for a train could calm themselves down.
Both of these things interested me, but the line from there to a classroom modeling task forces me to ask myself:
- What question would lead to that interesting knowledge?"
- Is there some way I can provoke that question visually?
- Could a student guess at that question?
- What information would a student need to answer that question?
- What mathematical tools would a student need to answer that question?
- Is there some way to confirm the answer visually?
So the next time you see something that's simultaneously a) interesting to you and b) mathematical, try running through those questions above and see how they'd play out. In the meantime, you can check out my specific answers above.
BTW. Many thanks to Chris Hunter for helping me brainstorm Bubble Wrap.