Beacon Lesson Plan Library

Float My Boat

Gail Stukey


Why will a small piece of wood sink, but a huge boat will float? Is it magic or is it density? In this lesson students will start with the same raw materials and come up with a wide variety of results in the use of density and the displacement of water.


The student uses a variety of measurements to compare and contrast the physical properties of matter.


-Aluminum foil: 10cm square piece for each child
-Shallow pan of water for each group of 4
-Newspaper to cover work surface
-Centimeter cubes: 100 for each group
-Science journal or notebook paper for each child
-Checklist duplicated for each student (see associated file)


1. Cut aluminum foil into 10cm pieces.
2. Obtain shallow pans (one per group of 4 students.)
3. Duplicate Checklist for students.(see file)


Note: This is an activity to follow an introduction to the properties of matter including a study of mass, volume, and density. Students compare the relative densities of aluminum foil boats in terms of their length, width, height of sides, and area of the bottom.

1. Ask the students what would happen if they threw a log in the water.

2. Ask why they think a boat will float but a small log will sink. Is the boat lighter in weight?

3. Tell the students that they are going to each build a boat from the same materials. Their goal is to see who can design a boat that will hold the most centimeter cubes without sinking.

4. Discuss the reasons a boat floats. Elicit suggestions as to what they could do to make their boats carry a maximum number of cubes.

5. Divide the class into groups of four. Assign the numbers 1-4 to the group members. Have them group their desks to form a table.

6. Student No. 1 should cover the desks the newspaper.

7. Student No. 2 should distribute the aluminum foil.

8. Student No. 3 should receive the pan of water and take it to the work area.

9. Student No. 4 will act as recorder and record the number of cubes each personís boat contains.

10. Before measuring each student will estimate the number of cubes his boat will hold. The recorder will record this information.

11. The students will design their boats. As each one is ready, he will float his boat and see how many cubes it will hold.

12. After all students have completed their boats and measurements, they will discuss the results. Why did the boat that held the most cubes do so? How was its design different from the design of the others in terms of (a) length, (b)width, (c) area of the bottom, and (d) height of the sides.

13. In his science journal or on notebook paper each student will make a chart showing the estimates and actual results of his groupís work. Then they will each write their explanations of the results.

14. Clean up: Student No. 3 will empty the container and dry it out. Student No. 1 will retrieve and discard the newspaper from the desks. Each student will take his boat home with him.


This activity addresses density in terms of the length, width, height of sides, and area of the bottom of the container. Assess the
chart showing the result of each group's work and the explanation of why particular boats could hold more cubes than others. Use the checklist in the file.

Attached Files

A Checklist.     File Extension: pdf

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