Using Icebergs to Teach Buoyancy and Density

A common misconception among students of all ages is that heavy objects sink and light objects float. While this belief may explain many examples, massive icebergs show that the density of an object, not its weight, is the cause of flotation.

In this article, we’ve highlighted lessons that allow students to model icebergs and to begin to explore the concepts of buoyancy and density. Although the formal definitions of these concepts are beyond the expectations for elementary classrooms, students should begin to develop an understanding of the types of objects that float and those that sink. Guided activity and leading questions can help students realize that weight is not the only determining factor of whether or not an object floats. Incorporating inquiry-based activity (see suggestions below) can also help students develop an informal understanding of buoyancy and density.

All highlighted lessons meet the Physical Science Content Standard of the National Science Education Standards for grades K-4 and 5-8. You can read the entire National Science Education Standards online for free or register to download the free PDF. The content standards are found in Chapter 6.


MODELING ICEBERGS

These lessons all call for the creation of “icebergs” by freezing water in rectangular containers or film canisters. We’ve also been told by teachers that water balloons are an inexpensive way to create model bergs. Just fill the balloons with water, tie and freeze, and then cut and peel away the balloon when you’re ready to use the models! By using a variety of container shapes and sizes, you can simulate the many types of icebergs.

Floating a Bergy Bit (Grades K-3)
Students create icebergs and observe that they float in salt water. An assessment activity is also available for download.

Floating Ice Volume (Grades 4-5)
Students will measure how much ice floats above and below water and calculate its volume. An assessment activity is also available for download.

Do-It-Yourself Iceberg Science (designed for Grades 6-8, modify for K-5)
In this inquiry-based lesson, students will experiment with their own film canister “icebergs” to explore the principles of floating icebergs and ice density. The focus on density and calculating volume is too advanced for most elementary students, but the overall experimental design and ideas for further investigation would be useful for most elementary classes.

Turn these lessons into inquiry-based activities! Ask students to plan an investigation to determine:

  • If the shape or size of an iceberg affects whether it sinks or floats
  • If the shape or size of an iceberg affects the percentage of ice above and below the surface of the water
  • If icebergs float in both salt water and fresh water
  • If the concentration of salt (salinity) affects whether icebergs float or sink
  • If the concentration of salt (salinity) affects the percentage of ice above and below the surface of the water

BUOYANCY AND DENSITY

While these general lessons don’t specifically focus on icebergs, they do help students develop an understanding about sinking and floating by comparing various objects. Students in grades 3-5 use the familiar sinking and floating context to focus on the principles of experimental design. Teachers may wish to combine these activities with the iceberg lessons above to fully develop the concept with their students.

Sink or Float? (Grades K-2)
Students make and test predictions about sinking and floating and classify objects according to whether they sink or float. Teachers can incorporate ice cubes into this lesson to focus on icebergs.

Sink It (Grades 3-5)
Students develop an experiment to test whether objects sink or float. Teachers can incorporate ice cubes into this lesson to focus on icebergs.


INCORPORATING LITERACY AND OTHER CONTENT AREAS

Incorporating reading, writing, and other cross-curricular activities helps students develop important skills and extends their knowledge. For high-quality children’s literature about icebergs, please see Icebergs and Glaciers: Virtual Bookshelf.

Growing Floaters and Shrinking Sinkers (Grades K-5)
Informational text (written at K-1, 2-3, and 4-5 grade bands) explores the concept of floating ice. At each grade band, the text is available in three forms: a text-only pdf, a full-color illustrated book (pdf), and an electronic book with recorded audio (Flash).

What’s Happening to the Emperor Penguins? (Grades 3-5)
Students learn about the habitat and behavior of emperor penguins and consider how icebergs might impact their ability to find food.

Summing Up the Disaster (Grades 3-5)
Students research the Titanic sinking and write and publish a newspaper article.


This article was written by Jessica Fries-Gaither. For more information, see the Contributors page. Email Jessica at beyondpenguins@msteacher.org.

Copyright August 2009 – The Ohio State University. This material is based upon work supported by the National Science Foundation under Grant No. 0733024. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. This work is licensed under an Attribution-ShareAlike 3.0 Unported Creative Commons license.

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