Your Name:  John Waeltz


Lesson Title: Make The Egg Float


Introduction: Students will be exploring how buoyancy changes in salt water when compared to fresh water.  They will be charting their results on a spreadsheet and a class graph will be created to display and analyze their results.


Grade or Age Level of Student(s): 2nd or 3rd Grade


Objectives: Students will understand the buoyancy differences between salt and fresh water.  Students will also understand that spreadsheets can be used to collect and process data to display results.


Standards Addressed:

1a. apply existing knowledge to generate new ideas, products, or processes.

4a. identify and define authentic problems and significant questions for investigation

4c. collect and analyze data to identify solutions and/or make informed decisions

6a. understand and use technology systems


Timeline: 60 minutes


Materials:  4 eggs

                4 clear plastic cups or glass mason jars, 16 oz size or bigger

(marked at the appropriate levels where they are to be filled, 12 oz, 16 oz, 20 oz, and 24 oz)

                 1 large container of table salt

                 4 spoons

                 4 small bowls

                 paper towels

       computer with Microsoft Excel or comparable spreadsheet program


Grouping Strategies:  There will be four groups of four.  They will enter their results into the class spreadsheet one group at a time.


Learning Activities:  This lesson is conducted in the middle of a science unit on oceans.  Points for discussion and procedures will be:

- Characteristics of salt and fresh water such as were it is found, similiarities and differences, etc. 

- Discuss some of the ways we explore oceans.

- Discuss how submersibles are able to dive underwater.  Key term: buoyancy.

- Pose the questions, Do things float better in salt or fresh water?  Children can discuss, make predictions, and give reasons for thought.

- Introduce the experiment and the method of recording to the students.  Discuss the materials needed and the safety issues (dont play around with the salt, dont break the egg, etc.)

- Group class into four groups of four.  Groups of four work best for this experiment. Have a student from each group gather materials, which consist of a cup or jar, bowl of salt, spoon, and an egg.

- Have a student from each group fill their container with water up to the mark.  Each container will be marked with how much water have.

- Have groups discuss and make predictions on how many spoonfuls of salt it will take to float the egg.  They need to record their predictions.  Teacher will be making rounds to help and settle any prediction disputes.

- Have students begin experiment.  They will put in a spoonful of salt, stir, and then put the egg in the container.  If it doesnt float, they can scoop it out with their spoon and repeat the process again, counting each time they put a scoop of salt in the water.

- Once experiment is complete, have one group at a time enter their water quantity, prediction, and actual spoonfuls into the spreadsheet.

- Once every group has finished, clean up and have them return to their seats.  Post the spreadsheet on the projector or television.  Begin discussing the spreadsheet and why it is being used (collecting and displaying information).  Show students how their numbers can be displayed on a graph and the different types of graphing options available.  Discuss which graphs would be good to show our information, such as the bar graph, and why others, such as the line or pie graph, will not work.  Print graphs and display in the class for all to see. 

- Discuss the results of the experiment using the data on the spreadsheet and bar graph.  Why does the egg float in salt water (the water is more dense)?  Compare results.  Did it take more salt to float the egg in a glass with more water?  Why (because it takes more salt to equal the density needed to float the egg)?  Does the density stay the same (look at the spreadsheet and chart to see if the salt content directly correlates with the amount of water and then discuss)?  Do you think the egg will float higher if more salt is added?  Why is this important for people to know this information (ships and submarines need to know the density of the water to be able to operate properly, etc)?  

- Questions students about the spreadsheet.  How does this graph help us come to our conclusion (quick data reference)?  What are some other things you think we could use spreadsheets and graphs for (list responses)?

Sample spreadsheet and graph for this activity is attached to this page and can be found at the bottom.


Diversity: Students with sight disabilities will have a "coach" describe what is going on throughout the experiment.

Students with hearing disabilities will have a written copy of what takes place during the experiment to follow along and participate.

ESE students will be paired with non-ESE students for assistance when conducting the experiment.


Assessment:  Students will be able to identify that salt water is more buoyant than fresh water.  Students will be able to list the functions of a spreadsheet and what types of graphs can be used for comparing data.



“How to Make an Egg Float.”  The Free Science Fair Projects Network.  2006.  Accessed 12 Apr 09.

http://free-science-fair-projects.com/Free-Science-Fair-Project.aspx?ProjectID= 5&Title= HowToMakeAnEggFloat

Waeltz, John.  Into the Great Wide Open: Technology Unit to Explore Oceans.  1996. Jacksonville University


John Waeltz,
Apr 20, 2009, 10:54 AM