After this activity, students should be able to:

• Explain that engineers design protective equipment for athletes in many sports.
• Explain that engineers often have to re-design, re-build and re-test before choosing a final design.

Does anyone like to watch sports, either live or on TV? Does anyone participate in any sport or multiple sports? Do you wear any gear when playing your favorite sport? Is the gear or equipment you use for actually playing the sport or for protecting the players? Many engineers work on designing equipment that keeps athletes safe. Let's brainstorm some different types of protective gear that engineers work on designing for athletic purposes. There are helmets, pads, mouth-guards, shin guards, etc. worn by players for protection. Can you think of other Olympic sports that require protective gear?

There are some Olympic sports that do not immediately come to mind that do indeed require protective equipment, including kayaking (life vests), cycling (helmet) fencing (mask) and ice hockey (gloves and padding). The activity that we are doing today mimics the concept of protective gear for athletes. You will work as an engineer to keep your athlete (in this case, an egg) safe during a impact.

Imagine that you are up high in a tree and are holding a bowling ball. As you sit on a branch holding the ball, you wonder if the ball has kinetic or potential energy. Well, the ball has no kinetic energy as it lies between your hands, since it is not moving, but it does have potential energy, since it is above the ground. You decide to release the ball and let it fall to the ground. As the ball falls, it has both kinetic and potential energy. Once it hits the ground, it no longer has potential energy. All the potential energy was converted to kinetic energy during the fall. After the ball stops moving, it will not have any energy left at all because all of the energy has been absorbed by the ground.

For this activity, we will drop an egg from a height of two meters (~6.5 ft)! By the time the egg hits the ground, it will be traveling very fast and will hit the landing pad with a lot of force. Your job is to engineer a landing pad which will absorb the energy so that the egg does not break upon impact. Without the protective landing pad that you make, the egg would most surely break from the impact of the fall.

Do you think that engineers usually build the very first design that they think of after a design session? If you answered no, you are right, as they almost never do! Usually, they have to test many, many different designs before they find the very best one that is ready to be replicated many times over. When engineers try again and re-design, re-build, and re-test, that process is called "iteration." Engineers often iterate many times before choosing the final solution to a problem. Today, your first design may not work; however, that is okay, because you get to be just like a real engineer and try again with a new design!

Before the Activity

With the Students

1. Review the concept of kinetic and potential energy, and explain how it applies to the egg drop. Draw a diagram of the egg dropping and have the students identify which type of energy the egg has throughout the process. (Answer: potential when resting above the ground, potential and kinetic when falling, nothing when still on the ground, as all of then energy would be absorbed by the landing pad)
2. Give the students the following guidelines for their landing pads (see Figure 1 for sample landing pad):

Figure 1. An egg-cellent landing pad! click for copyright

• The landing pad must be between 15 and 30 cm wide.
• The landing pad may be no more than 6 cm tall.
• They will only have 5 minutes to design the pad. It must be drawn on a piece of paper.
• They will get 15 minutes to build their designs.

3. Assign groups of two.
4. Give students 5 minutes to design and sketch their landing pad.
5. Have each group show their design to the teacher, who will check to make sure their design meets the guidelines.
6. After their design has been approved, students will be given 15 minutes to build their landing pad. It is important to keep the students on track during building so that they do not run out of time to test.
7. Once all the students are ready, begin testing. Measure a height of 2 meters (~6.5 ft.) off the ground and make sure all the eggs are dropped from the same height. (See Troubleshooting Tips for hints on dropping the eggs.) Set up the testing area somewhere outside, or over a tarp or thick layer of newspaper inside. Only one group at a time should test while the other students observe.

Figure 2. The egg-cellent test station. click for copyright

8. Once all the groups have tested, the groups with their eggs still intact can test again, but from a higher distance (try 2.5 meters, or 8.2 ft.). Keep raising the drop height if the eggs remain intact.
9. When all the eggs (or most of them, if time does not permit) have broken, give the students a chance to re-design, re-build and re-test their landing pads. Talk with the students about the importance of iteration and how real engineers often go through many cycles of design and testing before building their final design.
10. After the second iteration of landing pads has been tested, give the students time (one to two minutes) to present their new designs to the class. Encourage students to think about and discuss which designs worked best, and why. Which design features helped protect the eggs the best?

One challenging aspect of the activity is ensuring that the eggs fall straight down when dropped. One solution is to drop the egg through some kind of tube, such as a piece of PVC pipe or cardboard tube.

If doing this activity as part of the Olympic Engineering unit, lead the students to think about Olympic events that require protective gear.

Have the students research a company that designs protective gear for athletes. Contact the company to ask what kind of engineers work there and what sort of design work they focus on during their day-to-day activities. Try to talk with an engineer who designs protective gear, and see if they can visit the class, or send a letter giving more information about their work.