## What’s the Best Design to Float Your Boat?

By Bertina Banks, July 2, 2009

### Grade Level

- Middle School

### Category

- Product Design

### Subject Area

- Mathematics
- Science
- Technology

### Lesson Time

180 minutes for classroom activities

### Introduction

In this lesson students will draw on their factual understanding of buoyancy and density to design a boat that will float in water while carrying a load.
Students will view short videos on buoyancy and boat design.
Students will work in collaborative groups to answer the following question: Should different considerations be taken into account when designing boats based on their destination? For example: fresh water vs. salt water? If yes, explain and provide examples. If no, explain and provide examples.
This question will pique student interest in boat design.

### National Standards

**Science**

**Standard 8.**Understands the structures and properties of matter

**Standard 12. Level II**. Understands the nature of scientific inquiry 3. Plans and conducts simple investigations (e.g., formulates a testable question, plans a fair test, makes systematic observations, develops logical conclusions

### Objectives

Students will:

- connect their prior factual understanding of buoyancy and density to their boat design
- determine the volume of water displaced by an object placed in water
- identify that when the mass of water displaced is equal to or greater than the mass of the object, the object will float
- design a boat that will carry cargo
- compare various boat shapes to judge cargo-carrying capacity
- brainstorm and design a model for a boat that floats with a load (the best boat design will carry the heaviest load)
- present their design
- incorporate student and teacher feedback into their design

### Resources

### Materials

- computers with internet access
- modeling clay
- clear plastic container (the bottom part of a two liter bottle)
- tape
- metric ruler
- balance
- masses
- aluminum foil (1 meter)
- four craft sticks
- four toothpicks
- two straws
- tape
- glue
- projector (for viewing movies)

### Procedures

Prior to this lesson it is important to remind students of what buoyancy is and what affects it. Teacher will facilitate discussion based on a video about how boat design has changed over the years. Students will brainstorm about how their design correlates with its function.

**Day One: Introduction**1. Students will watch two videos on buoyancy. 2. Teacher will introduce Web sites that serve as resources to help students to design their boats. Say, “We will watch a brief video to review the principles of buoyancy. As you watch try to answer the following question: How can I explain what buoyancy is to my nine-year-old cousin?” Show students the video at: http://videos.howstuffworks.com/discovery/6540-mythbusters-lets-talk-buoyancy-video.htm (MythBusters: Let’s Talk Buoyancy, on buoyancy, etc., to be viewed before students design their boats.) 3. Say, “Next we will watch a video that applies the principles of buoyancy. Pay special attention to the considerations that were made during boat design throughout history.” Show students the video at: http://newali.apple.com/ali_sites/ali/exhibits/1000813/ (Note: Teacher may use entire video or choose sections depending on the length of the class; a summary of the narration is listed below: a) Opening to 7:10--Introduction b) 7:10 to 29:24--Science teacher Dr. Barbara Hagerman takes students through a lesson on the scientific principles of buoyancy, stability, displacement, and ballast. Information on Archimedes and questions from students are also included. c) 29:24 to 50:45--The scientific principles discussed in the previous section are put into practical application as members of the Discovery Expedition discuss the purpose and design of their replica pirogues and keelboat. Video of their construction and use on the river is included along with questions from students. d) 50:45 to 1:05:07--We are joined by Ike Hastings of the American Sternwheeler Association who discusses the purpose and design of sternwheelers. Images of construction and operation of sternwheelers are included as are questions from students. e) 1:05:07 to End—Final questions from students, information from boat builders on how they combat the prospect of a “waterlogged” boat, summary of science learned.) 4. At the close of class students will discuss what they learned about buoyancy and ship design.**Day Two: Design Challenge**(Note: Some of Day Two’s lesson may run over to Day Three.) 1. Say, “You are all designers. A thrifty cargo shipper is your client. You have been asked to design a boat that will carry cargo made from very simple materials. Here are the rules of the game:- You may use only the materials listed to build your boat.
- You may omit only one item from the listed materials. All others must be included.
- Your boat may be no larger than 50 cm in any dimension.
- When testing the boats, the last mass added to the boat (the one that makes it sink) must be removed from the boat before totaling the mass that the boat held.

**Day Three: Present and Reflect**1. Students will present their design to the class explaining the amount of load they were or were not able to carry. If students modified their design this should also be explained to peers and teachers. Teacher will facilitate reflection by using the following questions: a) Did some boat designs perform better than others (according to the data?) b) How is the winning boat designed? Draw a picture of it. Why do you think it could hold more pennies? c) Did how you loaded the pennies on the boat make a difference? What is the best technique for adding pennies to a boat? d) How did your estimate and actual number of pennies compare?### Assessment

The teacher will listen to and observe students as they work in small groups and individually.
The teacher will evaluate the students using the analysis questions listed above for Day 3.

### Enrichment Extension Activities

This lesson can be extended by students answering the following question: How many grams of water does your boat plus pennies displace when your boat is floating at maximum load capacity? Design an experiment to find out.
Or students can complete the “floating or sinking” activity:
a) Find twenty items from your environment (at home, in your classroom, or outside).
b) Sort the items into two separate piles; those you think will sink and those you think will float.
c) Create a spreadsheet using Excel to record your predictions. Save the spreadsheet according to your teacher’s directions. Predict which items will sink and which will float. Record your predictions.
d) Get a large container of water and test each item one at a time, by placing them into the bucket/bowl of water. Place a check mark by those items that you predicted correctly.
Questions and Analysis:
a) What do you notice about items that float? What do they have in common? What is different?
b) What do you notice about items that sink? What do they have in common? What is different?
c) Did any items seem to both float and sink?
d) Can you modify any of your collected items that sank and make them float?
e) Can you modify any of your collected items that floated and make them sink?
f) What conclusions can you make about what sinks and what floats from your observations so far?

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