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Lesson Plans

Cricket Wicket Knockdown Challenge for Grades 6-8

Summary

Grade Range
6th-8th
Group Size
2-4 students
Active Time
2-3 hours
Total Time
2-3 hours
Area of Science
Physics
Engineering Challenge
Key Concepts
Engineering Design
Credits
Ben Finio, PhD, Science Buddies

This engineering challenge is based on an internal competition designed by employees at Fluor Corporation.

Science Buddies is committed to creating content authored by scientists and educators. Learn more about our process and how we use AI.
https://www.youtube.com/watch?v=Bcwvwxesbmw

Overview

Teach your students about the engineering design process with this fun lesson plan. They will design and build a ball-launching machine to knock down a target. Optionally, they can enter their designs in the 2020 Engineering Challenge for a chance to win a cash prize for your school! Teachers, note that elementary school and high school versions of this lesson plan are also available.

Learning Objectives

NGSS Alignment

This lesson helps students prepare for these Next Generation Science Standards Performance Expectations:
This lesson focuses on these aspects of NGSS Three Dimensional Learning:

Science & Engineering Practices
Constructing Explanations and Designing Solutions. Undertake a design project, engaging in the design cycle, to construct and/or implement a solution that meets specific design criteria and constraints.

Optimize performance of a design by prioritizing criteria, making tradeoffs, testing, revising, and retesting.
Disciplinary Core Ideas
ETS1.B: Developing Possible Solutions. A solution needs to be tested, and then modified on the basis of the test results, in order to improve it.

There are systematic processes for evaluating solutions with respect to how well they meet the criteria and constraints of a problem.

ETS1.C: Optimizing the Design Solution. The iterative process of testing the most promising solutions and modifying what is proposed on the basis of the test results leads to greater refinement and ultimately to an optimal solution.

PS3.B: Conservation of Energy and Energy Transfer. When the motion energy of an object changes, there is inevitably some other change in energy at the same time.
Crosscutting Concepts
Structure and Function. Structures can be designed to serve particular functions by taking into account properties of different materials, and how materials can be shaped and used.

Systems and System Models. Systems may interact with other systems; they may have sub-systems and be a part of larger complex systems.

Materials

If you want to enter your device in the 2020 Engineering Challenge, you can only use the materials listed below. Each item has a maximum allowable quantity and a point cost (each) that will be deducted from your score. Note that you can cut the materials, but costs are not prorated; e.g., if you cut a piece of paper in half and only use half of it, it still costs 10 points.

Swipe left to see more
Construction Materials
Item Maximum Quantity Point cost (each)
Cardboard (max size 12"x12" or 30x30 cm) 1 10
2 oz paper or plastic cup 10 3
Wooden craft sticks (4 ½" or 11.5 cm) 10 1
Wooden pencils (circular or hexagonal cross-section, approx. 7–8" or 18–20 cm length) 10 1
Paper (printer/copier paper, not construction paper or cardstock; letter or A4 size) 10 1
Rubber bands (size 32, 3" long unstretched and 1/8" wide) 10 2
Cardboard tube (1 unit = 1 paper towel roll or 2 toilet paper rolls) 2 units 9 per unit
Roll of clear adhesive tape (Scotch® tape or equivalent, 1/2" or 3/4" width, max length 500") 1 10
Duct tape (up to 90 feet total, no more than 2" wide) 90 feet 20 (if any used)
Tools and Testing Materials (no point cost)
ItemQuantityNotes
Ping pong ball 1  
Ruler or measuring tape 1  
Scissors 1  
2 oz paper or plastic cup 1 Used to build the wicket

Wooden pencils 2
Rubber or plastic eraser (approximately 2"x1"x1/2") 1
Modeling clay, Play Doh®, or homemade dough. Enough to fill the 2 oz cup halfway
Table 1. Materials allowed for the 2020 Engineering Challenge.

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 and office supplies to build a device that will launch a ping pong ball at a target to try and knock it down (the target is called a wicket, inspired by the game of cricket). If you have not already, watch this video for an introduction to the challenge. If you want to enter your students' designs in the 2020 Engineering Challenge, make sure you review the official materials and rules before you begin.

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.
  • Conservation of momentum is yet another topic typically covered in physics classes. An object's momentum is equal to the product of its mass and its velocity. When two objects collide, their total momentum is conserved. Your students can examine what happens when the light, fast-moving ping pong ball collides with the heavy, stationary eraser.
  • 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

Prep Work (10 minutes)

Teacher Tool Box

Related Lessons

Engage (5 minutes)

Introduce the challenge to your students. Explain that their main goal is to build a machine that can launch a ball at a target and knock it down. However, there are rules they have to follow, and they are only allowed to use certain materials. First, show your students the introductory video:

https://www.youtube.com/watch?v=Bcwvwxesbmw

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

Rules

Launching Device

  1. Device can only be built with items on the official materials list.
  2. Device must be free-standing and rest on the ground or a cardboard base. It cannot be taped to the ground or another object like furniture. It cannot be held up in the air or supported by a person (if you let go of it, it shouldn't fall over).
  3. The device must launch the ping pong ball (e.g., using a rubber band or a lever). This launching action can be activated by a person, using one or two hands (e.g., stretching a rubber band, pushing on a lever). The device cannot just support the ball while a person throws the ball (e.g., like a golf tee—the device can't just hold the ball in place while you flick it forward with your finger).

Testing

  1. Wicket must be built according to the diagram shown in Figure 1.
  2. Wicket must be placed upright, at least 1 foot from the nearest wall or obstacle (Figure 2).
  3. Your launching device must be a minimum of 2 feet away from the wicket (Figure 2).
  4. Testing may be done by a team of up to four students (e.g. one student to launch the ball, one student to retrieve the ball, one student to reset the eraser or wicket, and one student to record the number of times the eraser is knocked over).
  5. The ball is allowed to bounce or roll on the ground before hitting the wicket. If a ball bounces off the wall or any object (including a student) and then knocks the eraser over, that does not count (Figure 3). It does not matter if the ball hits anything after hitting the wicket.
  6. The ball does not need to hit the eraser directly in order to knock it down. It still counts if the ball hits the cup or the pencils and makes the eraser fall.
  7. For the official test to calculate your score, there is a time limit of three minutes to see how many times you can knock the eraser off the wicket.
  8. You can do as many official tests as you want to try and get a higher score, but you can only submit one high score per team.

Do you have a question that is not answered by these rules? See the FAQ.

Image Credit: Ben Finio. Science Buddies / Science Buddies
Figure 1. The wicket is made from a 2 oz plastic or paper cup half-filled with modeling clay. Two pencils are stuck into the clay vertically, 1 inch apart, and an eraser is balanced on top. The goal is to launch a ping pong ball at the wicket and knock the eraser down.

Image Credit: Science Buddies
Figure 2. Minimum distances between the launcher, wicket, and other obstacles. The launching device must be at least 2 feet from the wicket. The wicket must be at least 1 foot from any nearby obstacles like walls or furniture.

Image Credit: Ben Finio, Science Buddies / Science Buddies
Figure 3. Illustration of how the ball can bounce before hitting the wicket. The ball can bounce off the floor multiple times, or roll on the floor, before hitting the wicket. The shot does not count if the ball bounces off other obstacles, like a wall or person, before hitting the wicket.

Explore (90 minutes)

  1. Have each group build their own wicket, as shown in Figure 1.
  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. 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 machine, they should set up the wicket (remember to make sure it is at least two feet away). Try launching the ball to knock the eraser down, and make observations. What happens when they launch the ball? How far does it go? How accurately can they aim it? How many timers can they knock down the eraser? If they do repeated launches, does their machine hold up, or start to fall apart? Depending on what they observe, they will need to decide how to modify or improve their design.
    1. Optional: as students are testing, ask them to explain (or draw a diagram) that shows transfer of energy to and from the ping pong ball when it is launched and when it collides with the wicket. For example, a slingshot initially stores potential energy in a stretched rubber band. When the rubber band is released, that potential energy is converted to kinetic energy of the ping pong ball. When the ping pong ball collides with the wicket, some of its kinetic energy is transferred to the wicket, causing it to move (and hopefully making the eraser fall!).
  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 knocking the eraser down more times within three minutes, and by using fewer materials. Can you improve your machine to make launching the ball faster and more accurate?
    Can you rebuild with fewer materials without sacrificing performance? Keep iterating until you are convinced you have the best possible machine, given all constraints.

Reflect (30 minutes)

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

  1. Set up one or more official wickets for testing.
  2. One at a time, let each group set their machine up at one of the wickets (remember to use a ruler or tape measure and make sure it is at least two feet away from the wicket!).
  3. Let the students load the ping pong ball in their launcher.
  4. Start the stopwatch and let the students start launching the ball. As soon as the eraser is knocked down, they can reset it and keep launching.
  5. Keep track of how many times the eraser is knocked down within the three-minute time limit.
  6. Move on to the next group.
  7. 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.

  • Did anyone draw designs that looked the same at first?
  • Did anyone draw a design that no one else thought of?
  • What problems did groups encounter during the building/testing process?
  • Do the best 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.

Make Career Connections

Discussing or reading about these careers can help students make important connections between the in-class lesson and STEM job opportunities in the real world.

Mechanical Engineer
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Career Profile
Mechanical engineers design and build machines with lots of moving parts. Did you enjoy designing a moving machine, figuring out what materials to use, and testing it to find out how well it worked? Read more
Engineering Manager
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Career Profile
Engineering managers supervise other engineers and make sure all the tasks are done well so that the whole project goes smoothly. If there's a problem, they're on the front lines of solving it. If you worked on the Knockdown Challenge as a team, did someone on the team take on the role of coordinating everyone? That's exactly the role of an engineering manager. Read more

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!

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