If you find that first act perplexing, feel free to follow up on all three. Four other notes:

• This one pairs nicely with the ticket roll problem. Try to imagine the tickets as really, really thin cars.
• In the second act, I offer this picture of a single Matchbox car. There aren’t any measurements and it bears perhaps only a passing resemblance to any of the cars in the picture. I like these moments a lot, though. The student has to estimate the dimensions of the car. Her estimate is entirely her own and will likely differ from that of her classmates. Everyone will own a different answer, then, even though they’ll all be developing proficiency with the same mathematical tools. Everybody wins.
• If you’d like to keep track of all the three-act tasks I’ve released so far, I have them logged in this spreadsheet, which is really insufficient but there it is.
• I just uploaded my first adventure with Google SketchUp. I designed it using blueprints I received because I asked for them.