Share with Your Students
Conductivity
1. Explain that conductivity is another property of matter.
Point out that materials that conduct electricity or heat
well have high conductivity and are called conductors.
Materials that conduct electricity or heat poorly have
low conductivity and are called insulators. Electrical conductivity is the measure of how well a material conducts
electricity. Thermal conductivity is the measure of how
well a material conducts heat.
2. Ask: Do you think the coating on an electrical wire
is a conductor or an insulator? (an insulator) Point
out that the different properties of materials, including
conductivity, often determine what kinds of jobs they
are used for.
Electrical Conductivity
Name
Date
Electrical Conductivity
STUDENT RESOURCE 1.4
ACTIVITY SHEET
20 minutes
Small Groups
1 Build an electrical conductivity tester like the one shown below.
Objectives
• Students build and use a device for testing electrical conductivity.
+
–
• Students rate the electrical conductivity of different common
materials.
2 Use the conductivity tester to test the different materials for
Materials
For each group
electrical conductivity.
3 Record your data in the table below. Sample data
Electrical Conductivity
Copyright © Houghton Mifflin Company. All Rights Reserved.
Best insulators
No light
plastic spoon
Best conductors
Dim light
Bright light
Very bright light
pencil “lead”
copper disk
glass dropper
jewelry
tongue depressor
aluminum foil
aluminum foil
1
plastic spoon
1
battery, D-cell
1
tongue depressor
1
battery holder
3
wires, stripped
1
bulb
*Not provided in kit
1
bulb holder
1
copper disk
1
dropper, glass
paper clip
CHEMISTRY • SECTION 1 PROPERTIES OF MATTER • 15
Student Resource 1.4 (p. 15)
1 pc.
1 pc. *jewelry, metal
1
1
Student Resource
• 1.4 Electrical Conductivity
Inquiry Focus
• Infer
paper clip
*pencil
1. Distribute the Student Resource.
Make copies of Student Resource 1.4, Electrical
Conductivity, and distribute to students.
SECTION 1 PROPERTIES OF MATTER • 9
Electrical Conductivity (continued)
+
–
A Testing for electrical conductivity
Teaching Tip
Step 2: Save the conductivity
testers for use in the Section
Assessment.
Teaching Tip
Step 3: Instruct students to
touch each wire of the circuit to
the glass part of the droppers, not
the rubber part.
2. Students make conductivity tester.
Have students make a conductivity tester, as shown. The
picture shows a paper clip in the position of the material to be tested. Explain that materials that conduct
electricity will allow electric current to move through
the circuit and light the bulb. The better the conductor,
the brighter the bulb will be.
3. Students test the materials.
Have students test each material in the conductivity
tester. Have them record their observations on the
Resource page.
4.Discuss the Resource page.
When students have completed the Resource page,
discuss the answers. Ask: What kind of materials
were good conductors of electricity? (metals) Point
out that other materials might also conduct electricity,
but metals are the best conductors.
Assessment
Ask: In which column of the table would you
expect an iron nail to be? Explain. (It would be in the
right column because it is a metal and, therefore, a good
conductor of electricity.)
Extension
Thermal Conductivity
Safety
Step 1: Use water that is hot
but will not burn. Test the water
on your own hand before distributing to students.
1. To each student group, pass out a tongue depressor,
a plastic ruler, a zinc strip, a copper strip, and a
plastic cup.
2. Pour hot water into each cup until the cup is half full.
Have students place each item into the hot water.
3. Every 30 seconds for three minutes, have students touch
each material above the cup edge with the tips of their
little fingers, as shown. Have them note which object
feels hottest.
4.Ask: What conclusions can you draw about the
thermal conductivity of the materials you tested?
(Plastic and wood are poor conductors of heat. Copper
and zinc are good conductors, but copper is better.)
A Testing for thermal conductivity
10 • EXPERIENCE SCIENCE
Section Assessment
Name
Materials
For each station
Date
STUDENT RESOURCE 1.5
ASSESSMENT SHEET
Section 1 Assessment
1
Vocabulary
Fill in each blank with the correct vocabulary term.
1 Table salt changes from a solid to a liquid at 800ºC and from
a liquid to a gas at 1465ºC. The
salt is 800ºC, and its
melting point
boiling point
1
*pencil sharpened at each end
with eraser
1
*pencil
move through silver easily. Silver has high
solubility
and low
conductivity tester
(from Investigate 3)
of table
is 1465ºC.
2 Silver does not dissolve in water, but electricity and heat
conductivity
Student Resource
• 1.5 Section 1 Assessment
.
Properties of Matter
*Not provided in kit
3 Draw lines to match each picture to the property it is used to
determine.
–
+
˚F
120
110
100
90
80
70
60
50
40
30
20
10
conductivity
solubility
boiling point
Conductivity
4 Predict the electrical conductivity of the different parts of a
wooden pencil. Use the conductivity tester to determine the
electrical conductivity of the eraser, wood, pencil “lead,” and
metal band of the pencil. Record your results in the table,
using the terms none, low, medium, and high.
Eraser
Wood
Pencil “lead”
Metal band
Prediction
Answers will
vary.
Answers will
vary.
Answers will
vary.
Answers will
vary.
Conductivity
none
none
medium
high
16 • CHEMISTRY • SECTION 1 PROPERTIES OF MATTER
Student Resource 1.5 (p. 16)
Copyright © Houghton Mifflin Company. All Rights Reserved.
0
1. Set up enough materials stations around the room to
allow one-third of the class to work alone at a station
during the hands-on portion of the assessment.
2. Make copies of Student Resource 1.5, Section 1
Assessment, and distribute to students.
3. Divide the class into three groups. While one group is
working at the stations to complete the hands-on
portion of the assessment, the other two groups can
be completing the top part of the assessment. Rotate
the groups through the stations until each has
completed the hands-on portion of the assessment.
4.Discuss the answers as a whole-class activity.
SECTION 1 PROPERTIES OF MATTER • 11