Cattaraugus Allegany BOCES Math Science Technology DeptCattaraugus Allegany BOCESOlean, New York, US,

July 23, 2008

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This document includes the Teacher's Guide and Student Activity Sheet for Learning Experience 9: Density Beyond Liquids.

This wiki version can be edited or built up with other materials on the same topic by members of the Curriki community. The entire Looking at Liquids collection is also available as downloadable PDFs.

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This resource received a 3* rating because it is part of Looking at Liquids Science Kit, which received a rating of 3-Exemplary in the Curriki Review System and which you can see here: http://www.curriki.org/xwiki/bin/view/Coll_cabocesmst/LookingatLiquids

**TEACHER’S GUIDE**

**Materials:**

*For each pair of
students:*

2 Student Activity Sheets for Learning Experience 9

Small square block of wood

Large square block of wood

8d nail

White marble

Gradulated cylinder

K’nex balance

Centimeter cube

Metric ruler

Calculator

Water

Chart paper

Felt tip markers

**Preparation:**

Read the background information on density and displacement in the Looking at Liquids Teacher’s Manual. (Please see PDF) Review with students how they found the density of the liquids in Learning Experience 8. Students should disassemble the K’nex balance once they have completed this learning experience.

**Basic Skills
Development:**

Gathering Data

Interpreting Data

Discussing

Following Directions

Measuring

Observing

**Evaluation Strategy:**

Students will find the densities of a variety of objects by finding the object’s mass and volume and using the equation Density = Mass/Volume.

**Vocabulary:**

mass

volume

density

displacement

submerge

**Objective:**
Students will find the density of various objects using the equation Density =
Mass/Volume. Students will find the volume of various objects by using a ruler
or by using displacement.

*How do you find the
density of an object?*

Discuss with students the meaning of volume of an object. The volume of an object indicates how much space the object occupies.

If the object is rectangular or square in nature, a ruler can be used to measure the length, width, and height of an object. Volume = length x width x height

Give each pair of students a ruler and a 1 cm cube. Ask each student to measure the length, width, and height of the cube. Write these numbers on chart paper and give the equation for volume. As a class, find the volume of the cube.

Volume = length/1 cm x width/1 cm x height/1 cm = 1 cm³

A second way to find the volume of an object is to measure the amount of fluid it displaces when it is submerged. If an object is placed in water, some of the water had to move out of the way to make room for the object. The volume of the water that was moved out of the way or displaced is equal to the volume of the object.

Give each pair of students a graduated cylinder with 10 mL of water in it. If the object is placed in the 10 mL of water, the water level will move up. The measurement of that water level minus the 10 mL equals the volume of that object. Ask each pair of students to place their 1 cm3 cube in their 10 ml of water. Students are to read the water level with the cube in it.

It should read 11 mL. 11 mL – 10 mL = 1 mL

Remember: an object must be completely submerged in water before an accurate reading for volume can be done. If necessary, students may need to push the cube underwater until it is submerged.

**Discussion Questions:**

How does the volume of the block compare with the rise in water level? *(1 cm³ = 1 mL)

Which method of finding volume would you use if you were trying to find the volume of a rock? Why?

Which method of finding volume would you use if you were trying to find the volume of a block of wood? Why?

Students should complete the Student Activity Sheet for Learning Experience 9. Discuss the results. (Student answers are approximate).

**Answers:**

1. Volume of the:

Marble 1 mL - displacement

Nail 1 mL - displacement

Small Square Block of Wood 2.5 x 2.5 x 2.5 = 15.625 cm³-l x w x h

Large Square Block of Wood 5 x 5 x 5 = 125 cm³ l x w x h

2. Mass of the:

Marble 3 g

Nail 8 g

Small Square Block of Wood 14 g

Large Square Block of Wood 104 g

3. Density (approximate) of the:

Marble 3 g/cm³

Nail 8 g/cm³

Small Square Block of Wood .896 g/cm³

Large Square Block of Wood .832 g/cm³

4. The marble should sink in glycerol. The marble has a
greater density than glycerol.

5. The block of wood should float in water. The wood’s
density is less than water.

6. The blocks of wood should have similar densities. Due to
the natural growth process of wood, the densities may be slightly different.
Students should understand that size does not change the density of an objects
made from the same material.

7. “B” has the greater density. “B” has the same mass as
“A”, however due to the fact it is smaller in volume, “B” has more matter
squeezed into a smaller space. Therefore, the density is greater.

**STUDENT ACTIVITY
SHEET for Learning Experience 9 **

**Name___________________**

DENSITY BEYOND LIQUIDS

1. Find the volume for each of the objects. Remember: if you use displacement to find the volume, the object must be submerged or completely covered in water.

Item | Volume | How did you find the volume? |
---|---|---|

marble | ||

nail | ||

small square block of wood | ||

large square block of wood |

2. Use the balance and gram masses to find the mass of each
of the objects.

Marble _____________________________g.

Nail _______________________________g.

Small Square Block of Wood ___________g.

Large Square Block of Wood ___________g.

3. Using the data collected on the mass and volume of each
object, use the equation Density = Mass/Volume to find the density of each
object. Use your calculators when necessary.

Item | Mass (g) | Volume (Remember: 1 cm³ is equal to 1 mL) | Density (g/cm cubed) |
---|---|---|---|

marble | |||

nail | |||

small square block of wood | |||

large square block of wood |

4. Will the marble sink or float in glycerol? Look back to Activity Sheet for Learning Experience 8 for the density of glycerol. ____________________

How do you know?______________________________________________

5. Which block of wood will sink or float in water?
_______________________

How do you know?______________________________________________

6. How do the different size blocks of wood compare in
density?

_____________________________________________________________

____________________________________________________________

7. After completing this activity, think about this
question. Suppose two balls, A & B have the same mass, but A has a greater
volume. Which ball has the greater density? __________

Explain your answer.
___________________________________________

____________________________________________________________

____________________________________________________________

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