Investigation 4, Current Attractions
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Author: Mary Katherine Van Orshoven
Date created: 02/14/2012 6:50 PM PDT ; Date modified: 11/04/2013 2:13 PM PDT
VITAL INFORMATION
Subject(s)
Science
Topic/unit of Study & time
allotment
Magnetism and Electricity ­ Building an Electromagnet
Grade Level
Grade 4
Standards
CA­ California K­12 Academic Content Standards
Subject: Science
Grade: Grade Four
Area: Physical Sciences
Sub­Strand 1: Electricity and magnetism are related effects that have many useful applications in everyday life. As
a basis for understanding this concept:
Standard c: Students know electric currents produce magnetic fields and know how to build a simple
electromagnet.
Area: Investigation and Experimentation
Sub­Strand 6: Scientific progress is made by asking meaningful questions and conducting careful investigations. As
a basis for understanding this concept and addressing the content in the other three strands, students should develop
their own questions and perform investigations. Students will:
Standard a: Differentiate observation from inference (interpretation) and know scientists’ explanations come
partly from what they observe and partly from how they interpret their observations.
Standard b: Measure and estimate the weight, length, or volume of objects.
Lesson Summary
Students discover that when an electric current flows through an insulated wire wound around a steel core, the steel
core becomes a magnet. They learn this happens because an electric current produces a magnetic field. They find out
where to wind the wire on the core to produce produce the strongest magnet.
They read about Oerstad's elctromagentic discovery in the district adopt curriculm and textbook.
Lesson Objectives
Students Objectives are to learn that:
1. A current flowing through a wire produces a magnetic field.
2. A core of iron or steel become electromagnetic when electricity flows through a coil of insulated wire surrounding the
core.
3. The magnetism produced by an electromagnet can be turned on and off. Time Allotment and context
1 hour.
IMPLEMENTATION
Instructional Format/ Model
Anticipatory Set
Students arrive into the class and there is a half sheet of paper on their desk. They do this half sheet to get their minds
into the science mode. On the worksheet is this question: If steel or iron is attracted to magnets, do you think you can make steel or iron into a magnet? Explain your answer using pictures, drawings or words.
Input
1. Propose making a magnet that turns on and off.
I tell students: I was thinking about a big old junkyard crane that I saw one day. The crane used this
huge magnet to lift cars and put them in the car compactor. The crane operator could turn the magnet
on and off. Can you make a magnet that will turn on and off?
Modeling
2. Review Magnetic interactions
I will have prepared a cup of washers and pour them into the well on a circuit base. I will use a magnet, a
steel rivet and washers to demonstrate the following.
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A) I will use a magnet to pick up washers and move them to another well.
I will tell students that the magnet works because the washers are steel and attracted to the magnet ­
I will say. "But can you turn off the magnet? Without pulling it away from the washers?"
B) I will use the magnet to pick up the rivet. (The rivet sticks to the magnet because it is steel)
C) I will now use the rivet stuck to the magnet to pick up the washers. I will say, " Do you see how the magnetism is given to the rivet by the magnet and you can't turn it off
without removing the magnet."
D) I will use the rivet by itself to pick up washers. I will say, "See how that does not work? The rivet is not a magnet. "
3. I say, "Today's challenge is this:
This is a steel rivet, but it isn't a magnet. Can you make a rivet like this into a magnet that will
turn on and off? "
Guided Practice
5. TACKLE THE MAGNET CHALLENGE GUIDED ( Depending on the students and how they have
performed on previous lesson, you may let them try this challenge unguided at first and if you
have time)
I say, "There is a long wire added to your tubs. The long wire may be useful for making your rivet into
a magnet that turns on and off. Start by winding the wire around the rivet like this. I show and start the
investigation for them by taking one wire and wrapping it around the rivet so that there are eventually two
ends showiing. Then I ask, " Where do you think we should attach the ends of the wire?"
This should be enough of a prompt to move most students in the correct direction. Observe the groups as
they work and guide or prompt as needed.
Independent Practice
7. Students will begin to work in their groups. Because they have been working with batteries, swithces,
wires, lightbulbs, etc... Expect a many of them to discover electromagnetism by attaching the ends of the
wire that is wrapped around the rivet to the to a switch and a battery. Some will forget the switch but
prompt them to think about turning off and on the magnet like we did with the lightbulbs.
I willl ask: HOW DID YOU MAKE A MAGNET THAT COULD TURN ON AND OFF?
Students may offer these ideas.
a) the wire must be wrapped around the rivet
b) the wire must be in a circuit/connection with a switch and a D­cell
c) the rivet is only a magnet while the circuit is closed
8. INTRODUCE ELECTROMAGNET
I tell the students, "You have discovered the electromagnet! An electromagnet is a piece of iron with
insulated wire wrapped around it to form a coil. While electric current is flowing through the coil, the piece of
steel is a temporary magnet.
9. FIND OUT WHERE THE MAGNETISM COMES FROM
Tell students:
Let's see if we can figure out why the rivet becomes a magnet. Earlier we used a magnet compass to detect
a magnetic field. Let's see if we can find out more about the electromagnetic using a compass. Try this! Again model for students under the docucam and then have them try it in their groups.
A) remove the wire from the rivet and reconnect the wire between the switch and the D­cell
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B) Place the compass on top of the wire
C) Close the switch briefly so current will flow through the wire
D) Place the compass on different places of the wire and test and re­test. 10. DISCUSS THE MAGNETIC PROPERTIES OF THE WIRES
Ask the students to remove the wires from their circuit bases. Then discuss the findings.
1) Which way did the compass needle point before you closed the circuit?
2) What happened when you closed the circuit? (the compass needle moved)
3) Why do you think the needle moved? (the wire became a magnet)
4) Was the wire a magnet the whole all the time? When was it a magnet ? ( No, only when current was
flowing through the wire)
Tell students:
When electricity flows through a wire, a MAGNETIC FIELD forms around the wire. The
MAGNETIC FIELD is only there while the current is flowing in the wire. As soon as the current
stops the filed disappears.
If the wire is wrapped around a core of iron or steel, like a rivet, the MAGNETIC FIELD will
INDUCE (or make happen) make magnetism happen in the piece of iron. The induced magnetism
is what makes the electromagnet. The electromagnet acts like a magnet as long as the current is
flowing in the wire wrapped around it.
10) FIND THE BEST ELECTROMAGNETIC DESIGN (MAYBE)
Tell the students that you noticed that just about everyone wound the wire around the rivet differently. Challenge them to work in their group to find the best location for winding the wire on the rivet to make
the round head of the electromagnet as strong as possible.
Work with students to set some standards so everyone will be able to compare results.
a) always use the same number of winds. 30 to 40 winds works best.
b) Pick up washers on the head of the rivet
c) Count the washers lifted to determine the strength of the magnet
d) More washers = more strength
Check for Understanding
11) ASSES PROGRESS
Observe students in groups to see who is meeting the challenge and using the standards
12) Share results with class. Have a few students from different groups explain their experiements.
13) Return the tubs with the science materials
14)Reinforce the Vocabulary
A) ELECTROMAGNET IS A COIL OF INSULTED WIRE, USUALLY WOUND AROUND A CORE OF IRON OR
STEEL, WHICH PRODUCES A MAGNETIC FIELD WHEN ELECTRICITY FLOWS THROUGHT THE WIRE. ELECTRO = prefix , MAGNET = root word.
B) THE CORE IS THE MASS OF IRON OR STEEL AROUND WHICH A WIRE IS WOUND
C) A COIL IS THE WIRE WOUND AROUND A CENTRAL CORE
D) ELECTRIC CURRENT IS A FLOW OF ELECTRICITY THROUGH A CONDUCTOR
15. MAKE CONTENT ENTRIES
A) What happens when an electric current flows through a wire? Answer: A magnetic field forms around
the wire)
B) How can you make a magnet that turns on and off? Answer: Wrap insulated wire around a steel rivet
or iron core and connect it to an electric circuit
C) What placement of the insulated wire on the rivet makes the strongest electromagnet? Answer: Wrap
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the wire between the head of the rivet and the first washer
D) How else can you change the strength of the electromagnet?
Answer:
­ change the number of winds
­ Add another D­cell
­ Use thicker wire
Closure
16) Read Electricity = Magnetism ­ In district adopted curriculum textbook
17) DISCUSS THE READING.
How does an electromagnet work? Answer: Current flowing through insulated wire creates a magnetic field. Winding the wire around an iron
core increase the magnet strength. the strong magnetic field induces magnetism in the iron core)
Why did the compass needle rotate when we ran electric current through the wire? Answer: When the current flowed through the circuit, the magnetic filed around the wire interacted with
the magnetic field of the compass needle. The interaction rotated the compass needle.
Student Grouping
Students are grouped in pairs of fours depending on their decisions at their table of four.
Differentiated Instruction
Assume no differentiated instruction for ELL, GATE, or Special Needs students. However, students will be grouped with
other students of varying skill levels and learning styles. Any Special Needs student will have an aide who assist them
with their lesson. MATERIALS AND RESOURCES
Materials/Resources
1 Rivet
1 Electromagnetic wire, 24 guage, 150 cm
1 Short 20 gauge wire (red)
1 Circuit Base
1 D­cell alkaline
1 Switch
50 small washers in cups
1 Compass
Technology/ Web Resources
None used in class.
ASSESSMENTS
Assessment/Rubrics
No assessment at this time. Sample Student Products
Author's Comments &
Reflections
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