Electromagnets (lesson four of eight)

Author(s): Ben Engel, Arthur Millius, Lisa Monti and Helen Wong-Lew

Lesson Overview

Grade level(s):

Grade 3, Grade 4

Subjects(s):

Physical Science, Science Skills

Topic:

Electricity and Magnetism

Big ideas(s):

Learn the difference between a control and variable. Design an experiment and test a hypothesis using the relation between electricity and magnetism.

Vocabulary words:

control, variable, hypothesis, experiment, test, electrical energy, magnetic energy, electromagnet

What you need:

Electromagnet kit, batteries, battery holders

Grouping:

pairs

Setting:

classroom

Time needed:

1 hour

Author Name(s): 
Ben Engel, Arthur Millius, Lisa Monti and Helen Wong-Lew
Summary: 

Introduce the scientific method, control and variable. Reiterate that electricity can be used to create magnetic energy and discuss the different properties of an electromagnet (number of batteries, number or wires turns, or material of wire). Students then take time to think of experiments varying these properties and then test their hypotheses by actually performing the experiment they thought of.

Prerequisites for students: 

Students should be familiar with the different forms of energy, know that they can be interconverted, and be familiar with the concept of wires conducting electrical energy.

Learning goals/objectives for students: 

Learning Objectives 1) Learn the difference between a control and a variable. 2) Design an experiment to test a hypothesis. Understand that only one variable can change during an experiment. 3) Learn that electricity and magnetism can be interconverted. Language Goals 1) Introduce the terms control, variable, and hypothesis. 2) Outline their experiment in writing, describing hypothesis, controls, and variables. 3) Record results in table form.

Content background for instructor: 

Teachers should have put together a working electromagnet and tried each of the experiments prior to the lesson.

Lesson Implementation / Outline

Introduction: 

Discuss the SCIENTIFIC CONCEPT: Electrical energy can be converted into magnetic energy and vice-versa. One example of this is the electromagnet, like the junkyard crane used to pick up cars.

15’ Discuss the SCIENTIFIC METHOD: The first thing to do is make a hypothesis, and then design an experiment to test the hypothesis. Importantly, the experiment must be appropriately controlled to make the results meaningful. Here,stress the importance of only changing one variable at a time. Allso stress that hypothesis are frequently wrong. You learn just as much from a wrong hypothesis (perhaps even more!) than from a correct hypothesis. Explain one example of a variable, which changes, while listing the controls and variables on the board. Fill out part of the results table in the form of an overhead.

Activity: 

10’ WRITING and THINKING: Before materials are passed out, students work in teams of two to come up with which variable they will change. They assess what the appropriate controls will be. They also make a prediction on what the result will be.

30’ EXPERIMENT: Materials are passed out according to which variable they chose (groups get specialized data tables). Everyone now makes the SAME electromagnet. This is important because they need to establish the controls for their experiment. They attempt to get the most number of washers on their magnet. If time permits, multiple trials can be done. Each group only changes one aspect of their electromagnet – the number of batteries, the number or wire turns, or the material the wires are wrapped around. Again they try to determine the maximum number of washers they can pick up with their electromagnet. They fill out their worksheet, noting how the variable changed and what results were obtained for that variable value. Students who have extra time can re-make their control electromagnet to see if the number or washers they can pick up has changed. They can also experiment with the spacing of the turns or choose a new variable.

Checking for student understanding: 

After clean-up we reviewed on a word wall the controls and variables from each of their experiments. That is, the students told the class what their control was, what their variable was, and what the result of their experiment was. They also had a chance to write this on their worksheet prior to the class discussion.

Wrap-up / Closure: 

We reviewed the concept that controls do not change from experiment to experiment, and that you should only change one thing (one variable) in an experiment.

Extensions and Reflections

Reflections: 

The idea of control and variable are difficult concepts. This lesson could have been broken up over multiple days. On the first day student would learn about control and variable and then plan their experiments. At the end of the first day, they would predict (make a hypothesis) about what would happen. On the second day, they would test their prediction, write their results, discuss their results and then write a conclusion. In addition, I would like to have students reflect on what a control means (in their own words) and what a variable means. This might be done by giving them another scenario (or experimental set-up) and asking the students to pick out the controls and variables in that setup.

AttachmentSize
Electormagnet general student wksht.doc40 KB
Electromagnet - material student wksht .doc25.5 KB
Electromagnet -batteries student wksht.doc25.5 KB
Electromagnet- turns student wksht.doc25.5 KB

Standards - Grade 3

Investigation and Experimentation: 
5. 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:
a. Repeat observations to improve accuracy and know that the results of similar scientific investigations seldom turn out exactly the same because of differences in the things being investigated, methods being used, or uncertainty in the observation.
c. Use numerical data in describing and comparing objects, events, and measurements.
d. Predict the outcome of a simple investigation and compare the result with the prediction.
e. Collect data in an investigation and analyze those data to develop a logical conclusion.

Standards - Grade 4

Physical Sciences: 
1. Electricity and magnetism are related effects that have many useful applications in everyday life. As a basis for understanding this concept:
c. Students know electric currents produce magnetic fields and know how to build a simple electromagnet.
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