Like pretty much anything good I do in my Algebra class, this is simply a slight modification of something someone else has created - in this case, Dan Meyer. Please go read his post - and the comments - for all the goodness.
But I thought it might be helpful for somebody if I shared the slight modification I've made to it to take advantage of Google Apps. Like many districts, we are a Google Apps for Education district, so I wanted to try to leverage that for this assignment and use Google Spreadsheets instead of Excel. I'm going to have the students gather the data outside of class, following these directions and using a copy of this Google Spreadsheet.
Then they'll come to class, hopefully with the printouts of their two graphs but, if not, I'll hopefully have their shared copy to pull up on screen if necessary. We'll then talk about sketching a line of best fit (they on their printouts, me on the smart board) and coming up with a rough equation for that line. We'll then discuss, hopefully teasing out the same questions that Dan talked about in his post.
Some folks might refer to this as a "flipped" lesson, as I'm having them doing the research outside of class and then we discuss in class. I don't much care what we call it, I'm just trying to maximize my face-to-face time with them and hopefully get them to engage in some interesting mathematical thinking. They'll have two nights to complete the research, which I'm hoping will only take them 20-25 minutes total.
While I'm not a huge fan of homework, given the restraints of our schedule (my Algebra class meets four days a week, 59 minute periods when no special schedules - PLC, assembly, testing, etc.) and the curriculum (still too much for even a 5-day a week, 90 minutes a day Algebra class), I feel reasonably good about 20-25 minutes with two nights to get it done. (Next year I'm hoping to give them 3 or 4 nights to do it, I just didn't figure it out in time this year.)
My interest here wasn't so much in plotting the points, which is why I've created the two graph tabs in Google Spreadsheet for them. My interest is more in the relationship between time and distance and cost and distance, and whether they can think that through. And then translating all of that to an equation to model it. I debated for a while with just giving them the flight/time/distance/cost information up front, as gathering that information isn't the essential part of this activity, but in the end I decided there was some value both in them learning about flights/cost and how to gather the information, and about how to organize it in a way that might help analyze it. I would be interested to hear your thoughts on that decision (as well as any of the other decisions I made with this lesson.)