How many of you have ever been bungee jumping? (No hands) How many of you want to go bungee jumping? (6 or 7 hands and a whole lot of excited responses of "that would be so cool" or "I don't want to die before I can drive")
Today, we're going to do some research for a bungee jump. What do you think are some important questions to ask before you step off the cliff? (Students almost always mention the strength of the bungee cord, how long it is, how much you weigh, and whether or not you have a death wish) Do you think there is a relationship between those things? Does it matter how much you weigh? How much does it matter?
Here's our bungee jumper. (Show students the paper clamp with some washers attached) We don't want to send a real person down while we're experimenting because it'd be a shame to kill someone just to gather data. Your groups will use our state-of-the-art bungee apparatus to figure out the relationship between how much the bungee cord stretches based on the weight of the person.
Hand out student worksheets. Demonstrate how to and how not to drop the bungee apparatus and gather data.
Let 'em loose:
I often start by having student groups present their graphs and lines of best fit. We compare and contrast group work. We talk about what we like and might do differently. Then we shift the conversation to a compare and contrast of what we like about the table, the graph, and the word descriptions. What do we like best? What information does each one present well? What information do we loose in each of them?
Then I have them use their graphs to estimate the amount of stretch for 18 and 30 washers. 18 isn't much of an issue. For 30 washers every group need to extend their graph and line of best fit. Plus, we get to have the conversation about the domain of our math model. Will the linear relationship between weight and stretch continue forever? Why or why not? It doesn't take a lot (if any) leading from me for students to see that the stretch will begin to level off at a certain point, or the rubber bands will simply break.
-it helps students make connections between tables, graphs and words (I don't get into equations on this one those that would be completely doable).
-it allows for some great conversations surrounding variables. What does it mean when we say something varies?
-once you have the materials, you can do this experiment with virtually no setup from year to year.
-it only takes one class period.