Calling for a Float

Challenge
Imagine during your cruise vacation you stopped on a deserted island to take in all of nature’s beauty. While you were enthralled by the untouched island, the cruise ship leaves! Now, you are only left with your cell phone and some random materials. Your cell phone doesn’t work at all on this island, but you know from a previous stop there is another deserted island where there is plenty of service. It is a short distance away and an easy swim, but how will you get there without damaging your cellphone? Your challenge is to build a contraption that will be able to float behind you while you swim to the other island.

Your cell phone raft does have some criteria and constraints. The raft has to be tied to your body so make sure to include it into your design. You can’t hold the contraption or the phone above your head since you need that arm to swim! Your phone needs to stay completely dry for fear of not working at all. Only the materials provided can be used in your design. While testing out the device, it can be pulled by the string from one end of the water to the other at a moderate pace.

Materials

• newspaper sheets
• rubber bands
• dental floss
• various kinds of tapes
• pencils
• scissors
• rulers
• tennis balls
• various string types
• plastic sealable bags
• old mobile phone

​
Hints and Tips for Success

1. Allow students planning and discussion time by having them experiment with a sample to see how items react in the water and what different ways they can be used.
2. After experimenting, allow student groups to plan their final design. Include as many ways to improve their contraption as needed.
3. If you don’t have enough old mobile phones for each group, use a deck of cards, soap dish filled with weight, or something similar.
4. For differentiation, adjust the amount of materials available, change some of the materials to more that float, make the contraption propel itself, not have the contraption travel across the water, show examples of floatation devices. Adjustments could be made to make it more challenging or simpler.
5. Ask reflection questions: Would the water be salty by the deserted island? Would that change how well your contraption floats? How could you test that? Would waves affect it? Why does a small little rock sink, but larger items float (barges, airplanes, cruise ships, etc)? What items do you wish you had to build the contraption?
6. Connect to science by having students discussing/figuring out buoyancy, density, sink/float, displacement of water, effects of electricity with water, waterproof and water resistant.
7. Connect to ELA by using the text, Captain Kidd’s Crew Experiments with Sinking and Floating by Mark Weakland, to introduce and provide background knowledge about floating and sinking with a pirate adventure.