Optional: video camera with slow motion capabilities

Introduce

The teacher should find videos showing different bungee jumps to get students thinking about variables and safety concerns in bungee jumping. After viewing videos, ask students, "If Barbie were going to bungee jump in the 'south stairwell' (tall location in your school), what are some variables to consider so she can predict how long to make the cord? She wants the longest jump that still keeps her safe." Discussion might include knowing how heavy or tall a person is, how much the cord stretches, how high the jump point is, and other variables. As discussion wraps up, explain the task below to students.

"Barbie will be attached to several rubber bands and dropped from a fixed height in [a pre-determined location and height in your room or building]." (Stairwells, foyers, or ladders work well. The teacher will need to determine location and height before beginning the activity! Do not share with students until they are ready to make their prediction.)

Remind students about proper use of rubber bands ("Do not snap, shoot, or otherwise misuse the bands").

Demonstrate how to create the double-loop that attaches to Barbie's feet. Also show how a slip knot can be used to add additional rubber bands. Students will need about 5 minutes to figure out how to connect the bands, and 15-25 minutes to collect the data.

Discuss how measurements should be made. What do we want to measure? Where is the origin? What units will be used? (SMP 2) [Zero is at the top of the meter stick and 100 cm on the floor, so they can measure the lowest point of Barbie' s head.]

Fig. 1 How to Make A Rubber Band Cord

Explore

Place students in groups of 3 or 4. Each group needs to decide as a group how they will drop and measure the distance Barbie falls. Remind students that the data they collect will be used for the next several days to determine their prediction of how many rubber bands will provide Barbie the longest, but still safe, bungee jump. Students will work through the Lesson 1 Activity Sheet in their groups.

Teacher Notes:

The activity sheet is intended for students to work through in groups. The teacher is walking around and listening to the group discussions. Prompt and cue with ideas or questions to check for and deepen student understanding.
Here are some questions you could ask students as they are working in groups:

“How many jumps will you need to test each length of rubber band bungie and why?” (SMP 4)

“Can you explain the procedure that your group will be using to take measurements?" (SMP 5)

“How close are your jumps at each length of your rubber band bungee?"

“Have you had any unexpected lengths or jumps you might consider outliers? Why?" (SMP 2, 4)

“What are you noticing in the scatter plot?" (SMP 7, 8)

“Could you fit a line to your data? What might the slope and y-intercept tell us?"

If time permits, students can share graphs with the class, or make a large graph to display in the room.

Synthesize

At the end of the lesson, have student groups share:

Method of collecting data

Graphs

Patterns they noticed about the shape of their graph so far

Initial predictions for the number of rubber bands they think they will need at this point

Teacher Reflection

How did you encourage groups to think about their measuring procedures?

How did you encourage students to resolve differences of opinions about the measuring procedures or predictions?

If you had any students who struggled to graph data points, what question(s) did you ask to get them to recall what they know about graphing?

How do we measure accurately and consistently? How can we use graphs and tables to present data? How can we use patterns in data to make a predictions?

Standards

CCSS, Content Standards to specific grade/standard

8.SP.A.1 Construct and interpret scatter plots for bivariate measurement data to investigate patterns of association between two quantities. Describe patterns such as clustering, outliers, positive or negative association, linear association, and nonlinear association.

8.SP.A.2 Know that straight lines are widely used to model relationships between two quantitative variables. For scatter plots that suggest a linear association, informally fit a straight line, and informally assess the model fit by judging the closeness of the data points to the line.

S.ID.6 Represent data on two quantitative variables on a scatter plot, and describe how the variables are related.

S.ID.6.C Fit a linear function for a scatter plot that suggests a linear association.

CCSS, Standards for Mathematical Practices

SMP 1 Make sense of problems and persevere in solving them.

SMP 3 Construct viable arguments and critique the reasoning of others.

PtA, highlighted Effective Teaching Practice and/or Guiding Principle CCSS

Implement tasks that promote reasoning and problem solving.