EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Inquiry teach on the introduction of Ohm’s law
Moritz Huegle
1. Topic of the lesson
The electrical resistance and the dependence on temperature
This lesson will use the dependence of the electrical resistance on the temperature to
introduce Ohm’s law and will also talk about PTC- an NTC-resistors.
2. Class
The lesson plan is taken from a unit about the concept of the electrical resistance in
physics. It is designed for an eleventh grade physics classroom.
3. Standards
The students will be measuring current, voltage and resistance in simple electrical
circuits with an analog and digital multimeter in order to record the information.
(Standards P-1.3 and P-4.4)
Working with voltage sources and the components of electrical circuits it is important for
the students to develop an understanding of how to work with electric instruments safely.
(Standard P-1.2)
Organization and interpretation of the collected data using tables, models and formulas
will be important in order to calculate the relationship between the three quantities in the
circuits introducing and using Ohm's law. (Standards P-1.5 and P-4.5)
4. Objectives
•
Students should be able to give examples of the dependence of the electrical
resistance on the temperature
•
Students should be able to distinguish NTC and PTC resistors
•
Students should be able to explain Ohm’s law and know about its area of
application
•
Students should be able to calculate current, voltage and resistance with the help
of Ohm’s law.
•
Students should be able to use scientific apparatuses safely.
•
Students should be able to develop, set up and execute experiments
•
Students should be able to analyze, evaluate and interpret the data afterwards.
•
Students should be able to present their results on a transparency in class
•
Students should be able to develop further social competences. They see the
importance of individual effort during group work and respect each other’s
results.
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EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Inquiry teach on the introduction of Ohm’s law
Moritz Huegle
5. Context
The present unit is about the electrical resistance. Its definition was introduced in the
beginning: R:=U/I (U is the voltage, I the current and R is the resistance)
The dependence on the material, length and cross section has been established
already. The resistance of light bulbs and energy saving lamps has been examined as
well. The explanation for the difference between light bulbs and other conductors will be
developed throughout this lesson. The electrical resistance depends on the temperature
explains the characteristic of the light bulb which is omnipresent in the students’
everyday life. The short discussion about the PTC- and NTC- resistance is just an
introduction in the many applications of the different characteristics of materials. Many of
those resistors are included in devices of our everyday life.
Ohm’s law is one of the most popular and most important laws in electricity. It is the
background for any complex electrical circuit and will be needed in the following lessons.
6. Materials
Items per group
-
Voltage source
-
two mounts and metal conductor, PTC- or NTC resistor
-
isolated cables
-
beaker with water
-
heating plate
-
a volt- and ampere-meter or a multimeter (analog or digital)
-
transparencies and pen
Items per student
-
Worksheet about the relationship about Ohm’s law and temperature dependence
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EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Inquiry teach on the introduction of Ohm’s law
Moritz Huegle
7. Instructional Sequence
Time
in
Min
Section
Planned process and activities
5
Quiz
Quiz about the electrical resistance
5
Review
“We have been talking about different
Methods
media
conductors such as copper and light bulbs and
we have analyzed different characteristics. In
which way did the light bulb differ from the
copper and why?”
 non-linear characteristic
 heat (increasing temperature of the wire)
 Temperature has something to do with
electrical resistance
5
10
Introduction
“What might happen if we heat conductors?”
Stating the
How can we examine that and connect it to our
problem
knowledge about the electrical resistance?
Developing
Students get together in groups and discuss
possible
their ideas, what they want to measure, why
experiments
and how
conclusions
-
Impulse
Group work
Heating a conductor with a flame ( too
hot too quickly, too much danger)
10
Heating a conductor with a water beaker
Instructions
Decision on one experiment:
Teacher
for
Heating a conductor with a water beaker
guided
experiments
Groups of three or four students
discussion
The lab procedures will be develop together at
Blackboard
the board (sketch, instructions, measurements
and tables for the data)
Each groups gets a pure metal conductor, a
NTC-conductor or a PTC-conductor to perform
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EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Inquiry teach on the introduction of Ohm’s law
Moritz Huegle
the experiment with
Safety instructions:
-
Caution, we are working with water and
electricity
-
Do not turn the power on while anyone
is still working on the set-up
-
lecture
Get back to your teacher before you turn
the power on
Slide or
Never touch the water or any wire in the
transparency
circuit while the power is on
-
Keep your measuring devices away
from the water beaker
-
Do not heat the water over 50°C
8. Assessment
The assessment will start right at the beginning of the lesson with a quiz about the last
lessons. After that the lesson will continue with the reasons for the differences between
conductors and a light bulb which is a review. The students will then develop an
experiment about how to measure the resistance of conductors at different temperatures
an perform the experiment. This involves the knowledge about multimeters and the
definition of the resistance. During the experiments they will be asked some questions
about what they are doing and why. The presentation of the results and conclusions with
the following discussion will also assess the student learning’s. And the worksheet will
give them the chance to apply their knowledge and review the topic of the lesson. The
results are checked at the end of the class.
9. References
National Science Education Standards (1996)
Retrieved August 23, 2009, from The National Academies Press
Web Site: http://www.nap.edu/openbook.php?record_id=4962
South Carolina Curriculum Standards (2005)
Retrieved August 23, 2009, from South Carolina Department of Education
Web Site: http://ed.sc.gov/agency/Standards-and-
Learning/AcademicStandards/old/cso/standards/science/
http://www.sn.schule.de/~ms16l/virtuelle_schule/3de/Kapitel_07_Ohmsches_Gesetz/kap
itel_06.htm
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EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Inquiry teach on the introduction of Ohm’s law
Moritz Huegle
10. Addendum
10.1 Worksheet: Ohm’s law
1. The resistance of a wire is calculated by measuring the current and voltage at a
constant temperature. The current was 0.1A and the voltage was 6V. Calculate
the precise value of R.
2. The wire is heated and its resistance is measured to be 90Ω. The voltage was
still 6V. How much current is running through the wire?
3. Is the above wire a PTC- or a NTC-resistance? Explain your answer.
4. The current through a wire with the resistance R=100Ω is I=0.05A. What is the
value of the voltage
5. Describe in your own words what an ohmic resistance is!
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