Key concepts
Engineering
Physics
Force
Speed
Design

Introduction
Do you play or watch a sport where you use an implement to move a ball? Golf, baseball, tennis—there are many different sports where players use something other than their feet or hands to move a ball. In this activity you will design, build and test your own sports equipment using recycled materials.

Background
How many sports can you think of where the athletes use something to hit a ball or a puck? Think about the size and shape of that item used in each sport. You'll quickly realize that they are all very different. A baseball bat is long and skinny, for example, whereas a tennis racquet is short and wide. Golf clubs and ice hockey sticks have long handles, but the head of a golf club is much smaller than the blade of a hockey stick. What do you think would happen if you tried to play hockey with a tennis racquet or baseball with a golf club? It probably wouldn't go very well!

Now think about the requirements for the equipment in each sport. They are all used to hit a ball (or puck), applying a force and changing the ball's speed or direction but in very different situations. Golf players hit a small ball that is sitting stationary on the ground, so they can do so accurately using a club with a small, heavy head while standing still. They need to hit the ball very far (hundreds of yards), which requires a powerful two-handed swing. Tennis players, on the other hand, need to move around quickly as they hit a moving ball back and forth across a net. Sometimes the ball is traveling more than 100 miles per hour. The wide face of the racquet makes it easier to hit the moving ball (imagine trying to do it if the racquet was the size of a golf club's head)—and using only one hand allows for more agility.

Now imagine that you want to play a game with your friends—but you don't have any racquets, clubs or sticks available, so you will have to build your own! But what you need to build will depend on what type of sport you want to play. You will need to use the engineering design process to make your own sports equipment.

Materials

• Assorted recyclable materials: plastic bottles, cardboard boxes and tubes, and so on.
• Duct tape and/or glue
• Scissors
• Pencil and paper
• Lightweight plastic or rubber ball (Ping Pong ball, Wiffle ball, and so on). Do not use a heavy ball, such as a baseball
• Open space, such as a large room or flat space outdoors
• Equipment (such as chairs and/or a table) you can use in your game
• A few friends to play your game with you (optional)

Preparation

• Decide what "sport" you want to play, and set up an area where you can play it. For example:
• You could play floor hockey by clearing some space in the middle of a large room and putting two chairs at opposite sides of the room. The legs of the chairs can form the "goals."
• >You could play "mini golf" by cutting out circular pieces of paper for "holes" and putting them on the floor, then setting up obstacles to form a golf course.
• >You could play table tennis by using some cardboard to make a "net" to go across the middle of a rectangular table.
• You could also make up your own sport or use an imaginary sport, such as Quidditch from the Harry Potter series.

Procedure

• You might be tempted to start building something right away, but engineers must work more systematically. First you will think through what you need to build and draw some sketches.
• Think about the sport you want to play, and what the "real" equipment looks like for that sport—or what you want the equipment to look like for an imaginary sport.
• Make a list of criteria for the equipment. For example, will you hold it with two hands or one? Will it need to hit a moving ball or a stationary one? Will the ball be in the air or on the ground?
• Look at the materials you have available. Think about how you could combine or connect them to make the equipment. What items could you use for the "handle"? What about the part that hits the ball? Will you need to cut or fold them? How will you connect them?
• Draw a sketch of your sports equipment and label the materials you will use.
• Now it's time to build! Try to build your sports equipment following the design in your sketch. You don't need to stick to your sketch exactly. You might discover that things don't work as planned. For example, maybe two pieces don't fit together like you thought they would. This is okay! You can go "back to the drawing board" if you need to make a change.
• When you are done building it's time to test. Try hitting the ball a few times (if necessary, depending on your sport, get a friend to throw or hit the ball to you). Can you hit the ball accurately? What about distance? Is your device easy to handle? Is it sturdy or is it too flimsy?
• Based on your observations decide if you need to make any changes or improvements to your device. You might even decide to start over and build a new one. Again, this is okay! This process is called "iteration." Engineers usually go through multiple iterations before arriving at a final design.
• Once you have arrived at a final design, build more copies of the device so you can play with your friends.

Observations and results
You probably discovered that you could build a simple device to hit a lightweight ball. For example, you can make a golf club or hockey stick by taping together paper towel tubes to form a handle and a plastic bottle to form the head. Your homemade sports equipment, however, was probably not as sturdy as the real thing. Most baseball bats, hockey sticks, and so on, are made from a single, solid piece of wood or metal. You probably had to use duct tape or glue to connect multiple pieces, for example taping multiple paper towel tubes together to make a handle. These joints introduce weak spots. Cardboard is also much flimsier than solid wood or the superstrong materials such as carbon fiber used to make tennis racquets. So while you can have fun playing your game you probably needed to be careful—your equipment might not have held up to too much abuse.

More to explore
The Physics of Sports, from Real World Physics Problems
She Shoots, She Scores! How Does Hockey Stick Flex Affect Accuracy and Speed?, from Science Buddies
Golf Clubs, Loft Angle, and Distance, from Science Buddies
How Tall Can You Build a Tower Before It Topples?, from Science Buddies on Scientific American
STEM Activities for Kids, from Science Buddies

This activity brought to you in partnership with Science Buddies