## Mass, Volume and Density

### Carol Houck

#### Description

Students compare and contrast mass, volume, and density of various objects.

#### Objectives

The student writes text, notes, outlines, comments, and observations that demonstrate comprehension of content and experiences from a variety of media.

The student knows that equal volumes of different substances may have different masses.

The student knows that gravity is a universal force that every mass exerts on every other mass.

The student knows that accurate record keeping, openness, and replication are essential to maintaining an investigator's credibility with other scientists and society.

#### Materials

Each group will need:
-One small paper cup
-A triple beam balance
-Small cup
-Enough peas, lima beans, and puff cereal to fill small cup
-Water

#### Preparations

A discussion of mass, volume, and density may be necessary prior to this activity.

Proper usage of the triple beam balance should be discussed and demonstrated prior to this activity

Peas, beans, and cereal should be measured out in advance of the activity.

#### Procedures

1 Arrange students in groups of three or four.
2. Inform students that they will be measuring the mass and volume of several objects and that this information will be recorded in a data table.

Part One: Determining Mass
3. Have students use the triple beam balance to measure the mass of a paper cup. Record the mass of the empty cup in the data table or laboratory journal.
4. Have students fill the cup level with the top with peas and measure the mass. Record the mass of the peas in the cup in the data table or laboratory journal.
5. Allow students to repeat this procedure with the cereal and the beans. Record all data.
6. The mass of the peas will be equal to the mass of the cup with peas minus the mass of the empty cup. This procedure should be followed for each item. Have students determine the mass of the peas, the beans, and the cereal. Record each mass in the data table or laboratory journal.

Part Two: Determining Volume
7. Have students fill the cup with water and then pour the water into a graduated cylinder. Measure and record the volume of the water. This is the volume of the empty cup. Record this volume in the data table or laboratory journal.

Part Three: Density Calculation: D = m/v
8. Students will determine the density of each item by dividing the mass of each item by the volume of the each item. For example, to determine the density of the peas, students divide the mass of the peas by the volume of the peas (the volume of the empty cup). Repeat this procedure for the cereal and the beans and record the information in the data table or laboratory journal.
9. Pose the following questions for concept development.
a. What is density?
b. Do all objects have equal density? Explain.
c. Do objects of equal volume have equal mass? Explain.
d. Do objects of equal mass have equal volume? Explain.
e. Which would be easiest to carry: a bag of cereal, a bag of peas, or a bag of beans? Explain your answer.
10. Have students discuss their answers and address any questions that result.

Optional Teacher Demonstration:
Demonstrate that various items may have the same volume but different mass, hence they have different densities. In a fish tank 3/4 full of water, place a full, unopened can of sugared soda and a can of diet soda. The sugared soda will sink because it is more dense. Place two pieces of fruit, approximately the same size, in the water. One piece should be unripe, the other ripe. The riper one with more sugar will sink deeper than the other piece. Compare a bar of one brand of soap with an equal size bar of another brand of soap to see which sinks or floats.

#### Assessments

The following questions may be used to assess understanding.

1. An object with a very large mass and a very small volume would be considered
a. very dense
b. weightless
c. not dense
d. none of these is correct

(answer a: An object with high mass and low volume is very dense.)

2. A cup of cereal and a cup of sand do not weigh the same. What explains this observation?
a. The cereal and the sand do not have equal volumes.
b. The cereal and the sand have equal densities.
c. The cereal and the sand do not have equal densities.
d. The cereal and the sand have equal masses.

(answer c: These two items must have different densities; same volume, different weight.

3. Why might a cup of sand weigh more than a cup of cereal?
a. The sand has fewer atoms packed in the cup.
b. The cereal has more atoms packed in the cup.
c. The sand has more atoms packed in the cup.
d. The cereal and the sand have equal masses.

(answer c: The sand has a higher density. There are more atoms packed in the cup of sand.)

The following may be used as a writing prompt for assessment:
As a traveler, you quickly learn that careful packing lets you put more items in a limited space. Certainly, when you backpack, you want to put the most itmes in the smallest space. You also want to find the supplies that provide for your needs but have less mass and volume. You decide to explore this concept with the food you plan to take on your trip. What types of foods should be taken, and why?

Group learning may be assessed by the rubric in the Associated File.

Self-Reflection:
Do you really need to carry around all those things in your backpack? How could you condense these items so that the mass is different?

#### Extensions

Often travel magazines or fashion magazines offer advice on how to pack your luggage. Compile a list of packing -do's and don't's-.

Astronauts need to have suits to keep them alive under extreme conditions. The suits can not be too bulky or heavy; this would restrict astronaut movement. Use the Internet to find out what materials are used in astronaut's clothing.

#### Attached Files

Group Learning Rubric      File Extension: pdf