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Susan Working

Mathematics Professor

Email: susan.working@gcccd.edu

Phone: 619-644-7290

This project is excellent when you have completed the chapter on lines. It has students create their own data and graph it and then choose a reasonable line, which represents their data. From there, they find the equation of their line (this will be unique for each group since each will be working with a different Barbie Doll) and answer questions related to their doll’s bungee jumping habits using their equation.

**Applicable Courses**

Elementary or Intermediate Algebra

**Background**

Plotting points, slope, point-slope form, slope-intercept form, extrapolation, linear modeling

**Materials needed**

Barbie Bungee Worksheet, Barbie doll, tape measure, scotch tape, bag of same-sized rubber bands, graphing calculator, pencil, paper, and straight edge.

**Extensions/Discussions**

- Use calculator to find the best-fit Linear Regression line
- What does the y-intercept represent in this context?
- What does the slope mean in this context?
- Does your equation make sense? If not, what could have gone wrong?

**How to do this project:**

The student will be put in groups of 3 or 4. Each group will require a Barbie doll. Each group will require approximately 40 rubber bands total. I always buy them from Office Depot or Staple and I choose the package with the #32 rubber bands (3” x “). These work best in my opinion. Each group will also need a 60-inch tape measure. I use sewing tape measures – they are fabric and easy to put up.

The tape measure should be taped on a flat wall vertically. The students attach rubber bands to Barbie’s feet (ankles). Use one rubber band to bind her feet together and then the students can attach each rubber band from there. Starting with one or two rubber bands, one student will hold the Barbie at the top of the tape measure with one hand and hold the end of the rubber bands with the other hand. Let her go and 2 other students should estimate how far she bungeed. Do 3 bungee jumps per rubber band quantity. Students continue collecting data until their Barbie falls beyond the tape measure and they are unable to collect any more data. Next they start their calculations – beginning with the average of each of the 3 jumps per rubber band quantity. I have my students round to the nearest tenth. After this initial set up the worksheet becomes self-explanatory. Again, I think it best not to work with fractions. Let your students use a calculator and round necessary calculations to the nearest tenth (for example, slope).

I also use graphing calculators to have the students plot their data points and then check the equation of the line which they have come up with. If the line is above or below all their data points or if the slope seems off then they know they have made an error in their calculations. It gives them a chance to go back and find their mistake. This can be removed from the packet if graphing calculators are unavailable. A worksheet on plotting data points is given at the end as well in case your students or you have never used this feature.

A nice ending to this project (#11) is to find a high spot that the students can bungee their Barbie dolls. For example, the bleachers of a football field works well. You will need to measure the distance from the top to the ground ahead of time. Then give the students the distance in class and tell them to compute how many rubber bands they will need in order to bungee their Barbie dolls. Have them attach the rubber bands and go test it out. The group who comes the closest to the ground without “killing” Barbie wins – you can give them a prize or extra credit or a pat on the back! The group who took more time to estimate their data collection accurately and pick out an appropriate line and work their algebra correctly will prevail!

This project normally takes two 50-minute class periods. The data collection takes approximately 20 minutes and then the students (as a group) can easily find the equation of their line – it should be the same for each member of the group. As homework, have them complete all questions through #10. On the second day is when you want to do #11 – the big finale. Have fun.

Worksheet | How to Plot Points and Graph on the TI 73

Susan Working

Mathematics Professor

Email: susan.working@gcccd.edu

Phone: 619-644-7290

PLEASE NOTE: This link will take to a website outside of the college site.