Volume, Mass, and Density Boxes

Target Subject: Physical Science

Purpose

To introduce the relationships among changes in volume, mass, and density

Background information

Density is a tough concept for all students to understand. However, during an introductory physics course, density is an important concept. Several density kits are available commercially form science education supply catalogs (See product tips section of this website) However a hands-on activity for students to create their own density boxes allows for a better grasp of the varying concepts involved.

Preparation

Collect several boxes with lids. These need to be the same size for each group. Gift boxes are easy to measure and they come in multiple sizes. Filling the boxes with sand, cotton balls, or crushed paper produces boxes with differing masses that are easily discernible kinesthetically by lifting the boxes.

Having students create the boxes provides an opportunity to practice measurement techniques as well as makes them aware of the equivalent masses. You can then compare the sizes and masses (weights) and do the math to figure the densities. The following is an example of what a data collection chart might look like comparing cotton balls, crushed paper and sand:

Group	Group 1	Group 2	Group 3
Box Volume	20 cm3	15 cm3	9 cm3
Box Mass 1	25 g	25 g	25 g
Box Mass 2	50 g	50 g	50 g
Box Mass 3	100 g	100 g	100 g

Materials

To create cotton ball box where the density of the cotton balls can be increased and measured. Other box volumes can be used.

• Empty box – Volume 10 cubic inches
• Empty box – Volume 3 cubic inches
• Cotton balls about 30
• Talking scales
• Pan balances tactile or talking linear measuring equipment
• Sand
• Crushed paper

Procedure

1. Count the number of cotton balls.
2. Place all the cotton balls into the larger box.
3. The density of this container of cotton balls can be expressed as 30 cotton balls per 10 cubic inches, or 3 balls per cubic inch.
4. Next place the cotton balls into the smaller container compressing them to make them fit.
5. The container is 3 cubic inches in volume. Now calculate the density of the contained cotton balls, and write as cotton balls per cubic inch. The density of this container of cotton balls is 30 cotton balls per 3 cubic inches, or 10 cotton balls per cubic inch.
6. This illustrates the idea of particles of matter being closer together in an object with greater density.
7. Compare how the boxes feel when you lift them.
8. Compare the masses of boxes of cotton balls to boxes of sand or crushed paper of the same volumes as described above.