Volleyball Machine Challenge for High School

Background Information for Teachers

This section contains a quick review for teachers of the science and concepts covered in this lesson.

In this lesson, your students will use readily available craft/office supplies to build two machines that can launch a ball back and forth over a net, similar to the game of volleyball (although in this case, the machines are allowed to catch the ball). The 2019 Engineering Challenge had specific rules and limits on what materials students could use. You can choose to follow the same rules, or just use this lesson as an inspiration. If you have not already, watch this video for an introduction to the challenge.

This challenge allows you to explore some interesting topics in physics and engineering. Rather than explain these topics in detail, this background section will give you a brief overview of each one, and you can decide which, if any, to address with your students. There is more information about these topics in the Additional Background section.

• Simple machines: use the project to learn about simple machines like the lever and the inclined plane. How can simple machines be combined to form a more complex machine that can launch a ball?
• Projectile motion is a classic topic in physics classes. How do the initial velocity and launch angle of the ball affect its range? What trajectory (i.e. a high, steep trajectory or a low, shallow trajectory) makes it easier to catch the ball?
• Energy is another classic physics topic. The ball needs kinetic energy, the energy of motion, to fly through the air. Where will that energy come from? It could come from elastic potential energy, the energy stored in a stretched material, like a rubber band. It could come from gravitational potential energy, the energy stored in an object that is raised up off the ground. Or, the energy could come from work that you do with your hand by exerting a force.
• Engineering design: you can also use this project to walk your students through the engineering design process. They probably will not build a perfect machine on their first try. Instead, they will need to iteratively test and redesign their launcher/receiver in order to improve the design.

Additional Background Links

• Simple Machines: Facts, Science Trek
• The Physics of Catapult Projectile Motion, Science Buddies
• What is a Projectile?, The Physics Classroom
• Engineering Design Process, Science Buddies

Prep Work (10 minutes)

• Gather all the materials you will need.
• Print the student worksheets if you will be using them.
• Optional: assign the introductory video for your students to watch before class.

Engage (5 minutes)

Introduce the challenge to your students. Explain that their main goal is to build two machines that can launch a ball back and forth over a net, like in a game of volleyball. However, there are rules they have to follow, and they are only allowed to use certain materials. First, show your students the introductory video:

Then, go over the student worksheet (rules also included below).

Explore (90 minutes)

1. Have each group build their own net. The net dimensions are shown in Figure 1.
   1. Tape two letter-size (8.5×11" or 21.6×28 cm) pieces of paper together along the 11" edge, overlapping by 1/2" (1.25 cm).
   2. Fold the resulting larger piece of paper in half width-wise, so it is 16" (40.6 cm) long and 5.5" (14 cm) tall.
   3. Prop the paper up to form an upside-down "V" shape. The bottom edges of the paper should be 2" (5 cm) apart. Tape the net down to a work surface like a table or the floor.

2. Design: before they start building, encourage your students to sketch potential designs for their machines. Each group member can start out by sketching their own ideas, then they can compare. They have a range of different materials available to them. What materials will they use for what purpose? Different group members probably have different ideas. Ask questions to evaluate the suitability of the different designs. How well does each idea follow all the rules for the competition? What about the limitations on materials? Can they evaluate all their proposed ideas and agree on which one they should build? What about combining aspects of different ideas into one new design? Remember that the two machines do not have to be identical.
3. Build: once the group has agreed on designs, they should build prototypes. They might discover right away that things do not always go as planned. Maybe the pieces of their design do not fit together as well as they planned, or the materials are not strong enough to do what they expected. Remind students that this is OK! They are allowed to modify their designs to improve them when they discover problems.
4. Test: when students are ready to test their prototypes, they should come up with a plan to systematically test the machines and identify areas for improvement. What happens when they test their machines? How many times can they get the ball over the net before it hits the ground or gets stuck? What improvements could they make for better performance?
5. Iterate: engineers rarely get something perfect on the first try! Now that they have tested their design once, it is time to improve it and retest. Look at the scoring document. There are two ways you can improve your score: by launching the ball back and forth more times within the time limit (without letting it touch the ground), and by using fewer materials. Can you improve your machines so they are less likely to "drop" the ball, allowing you to get it over the net more times? Can you rebuild with fewer materials while maintaining functionality? Keep iterating until you are convinced you have the best possible machine, given all constraints.

Reflect (30 minutes)

Once students have finished building their machines, have a class-wide competition to calculate official scores.

1. Set up a single official net for testing.
2. One at a time, let each team bring their two machines to the official net and set them up. One student can operate each machine.
3. Let the students place the ping pong ball in one of their machines.
4. Start the stopwatch and let the students start launching the ball over the net. Count how many times the ball goes over the net. Remember that students must wait for the ball to come to rest after each time they launch it. They are not allowed to touch or manually relocate the ball.
5. Keep going until the ball touches the ground or five minutes is up, whichever comes first.
6. Write down the number of times the ball went over the net for that group. They will need this information to calculate their score.
7. Move on to the next group.
8. If time allows, you can let each group go more than once to try and get a better score.

Discuss the results of the competition as a class.

• How similar/different were the designs people drew initially?
• How similar/different were the designs people decided to build?
• What problems did groups encounter during the building/testing process?
• Do the most successful designs have anything in common?

Assess

• Collect your students' worksheets and use them to assess how they worked through the design process.
• Ask each group to do an oral presentation about how their design worked, the engineering challenges they faced, and how they addressed them.

Lesson Plan Variations

Did your students enjoy this type of hands-on project? Check out the other Engineering Challenges and try them in your classroom!