Science 9

Core Unit: Using Electricity

Unit overview

Static electricity is a common phenomenon. Whether using it to shock friends on dry winter days or watching displays of summer lightning, or even walking around with a sock stuck to the back of our shirt, we have all seen and experienced static electricity. What causes static cling? Why are gasoline transport trucks 'grounded' before they load or unload? Why do balloons stick to the walls after they have been rubbed on a sweater? Why is there a market for anti-static pads to put under computers? How do anti-static pads work?

In contrast with static electricity, which seems to have more annoyance value than practical use, current electricity has a number of functional applications. This unit introduces students to some of the basics of electrical circuits and to the phenomena of static electricity.

Science writing and reading activities, as discussed in this Guide, should be incorporated into each lesson. Writing in personal, reflective journals, reading from newspapers, and reporting on the activities of science class in a variety of ways are only three strategies through which students may refine their understanding of the concepts of science and develop their ability to communicate through the written word.

Science challenge, as described in this Guide, is meant to extend students' critical and creative thinking abilities in the context of the science concepts being studied. Activities involving science challenge are included in the Suggested activities section of this unit. By giving students an opportunity to investigate the questions that arise from the investigations they have done, any activity can be extended to become a challenge activity. Science challenge is intended to give each student a chance to investigate an area of interest in more depth than would be possible for all students in a class to do. Science challenge is a key strategy for bringing the Adaptive Dimension to the classroom, and for encouraging independent learning.

Factors of scientific literacy that should be emphasized

Concept development

Foundational and learning objectives for Science and the Common Essential Learnings

Recognize the properties of static electricity .
1. Explore ways of producing, preventing production of, and removing static electrical charges.
2. Describe the characteristics and effects of static charges.
3. Explain static charges in terms of electron transfer.
Inquire into the principles of electric circuits .
1. Investigate the concept of a conductor.
2. Construct simple circuits which use various combinations of conductors, dry cells, switches, and bulbs.
3. Identify parallel branches and series branches within a circuit.
4. Discuss the measurement of the rate of flow and the potential for work in electric circuits.
5. Determine how to use meters to measure the voltage and amperage in various parts of a circuit.
Explore the relationship between electricity and magnetism .
1. Observe and describe the effects of magnetic fields and electrical fields.
2. Compare the characteristics of static and current electricity.
3. Examine the production of electric currents by interactions between moving magnetic fields and copper wire coils.
Develop students' appreciation of the value and limitations of technology within society. (TL)
1. Explore the prevalence and uses of electricity and electrical devices in the home, school, and community.
2. Identify the benefits and risks of electricity and electrical devices within the home, school, and community.
3. Assess how the use of electricity and electrical devices has shaped our society and our lives.

Suggested activities

Create a device to detect static electric charges. Consider ways to calibrate it to estimate the magnitude of the charge.

Determine as many ways as possible to produce a measurable static charge. Use the static detector developed in the first part of the activity to determine whether a charge is produced.

Factors: A5, B7, B8, B9, C5, C14, D1, F1
Objectives: 1.1, 1.2
Assessment Techniques: rating scales, presentations, short answer test items
Instructional Methods: problem solving, model building
In groups of two or three students, brainstorm for about five minutes to produce a list of what they know about lightning and questions they have about lightning. Collect these ideas and questions to form a class list. Generate more questions from the ideas on the list. Assign one question to each group. Have the group produce a poster which supplies some information about the question. Post these on the bulletin board around the question list. Encourage students to add new questions to the list.

Factors: B5, B13, C9, C14, E4, F1, G6,
Objectives: 1.2
Assessment Techniques: rating scales, written assignments
Instructional Method: research projects
Using a 1.5 volt dry cell and a 20 cm piece of 18 gauge wire, make a flashlight bulb light. Once students have mastered that, distribute bulb holders. Ask the students to experiment with using 2, 3, and 4 cells connected in a variety of ways to light one bulb, seeing how many bulbs can be lit with one cell, and other combinations of the four components. Have them diagram each set of connections.

Factors: A4, B13, B16, C11, C16, D3, E3, F5
Objectives: 2.1, 2.2
Assessment Techniques: observation checklists, performance assessment
Instructional Methods: problem solving, conducting experiments, explicit teaching
Design a machine in which an electrical circuit is a functional part. The machine can perform a useful function or it may have entertainment value (or both).
Invent ways of determining if electrical fields or magnetic fields are present.
Refer to questions in the unit overview. Find out some answers, ideas, or explanations.
Brainstorm, in groups of three or four, for five minutes to create a list of all the ways electricity has been used by the members of the group since they got up in the morning. Then, for each instance listed for the use of electricity, propose a substitute means of accomplishing that task without electricity.

Use the list of substitutes to create a story about the day in the life of a student in an "electricity-less" world.
Form student pairs and ask each pair to make a concept map or web about the concept 'electricity'. Then form groups of two or three pairs to compare, discuss, and explain the concept maps. For each concept map, ask the large group to identify one area where the map could be enhanced or expanded.
Through each long edge of a 30 cm by 15 cm strip of corrugated cardboard, evenly space 5 brass paper fasteners. Splay the arms on the backside of the cardboard so that none contact the others.

Use insulated wire or aluminum foil to make one or more circuits connecting some of the fasteners. Not all fasteners need be included in a circuit. If aluminum foil is used, masking tape can be used to isolate one circuit from another. Tape a piece of paper over the back to prevent the circuits from being seen. Exchange circuit boards with another person or group.
Construct a circuit tester to determine which fasteners are connected. By making connections between the heads and the fasteners on the front of the board, deduce where the connections have been made. Draw a diagram of what the back side of the board would look like. Front and back views of a sample board are drawn below.

This idea can be adapted to produce a question and answer board, where the connection of the terminal beside a question with the terminal beside the correct answer will cause a light bulb to glow.
Examine the wires inside a lightbulb which has had the glass removed. Is there a filament connecting the two heavy wires? Do the heavy wires come from the same place at the bottom of the bulb? Draw a diagram of how the electricity might flow through the bulb.
Use paper clips and brass paper fasteners to make a switch in a circuit. Find out how to make a parallel circuit and a series circuit. Experiment to discover the ways that switches work to control these circuits.
How do fuses and circuit breakers work? Why are they important parts of electrical circuits? Design a fuse to use in a circuit. Make a poster to explain to grade 4 level students how your fuse works.
Make a device which can be used to test whether a substance will conduct electricity. Demonstrate to your teacher that the device works. Can you find any non-metallic conductors or any metallic insulators?
Make a flashlight, complete with switch, two dry cells in series and a bulb with a reflector. The flashlight may have a similar design to a regular tubular flashlight or it may be of an innovative design. Make it sturdy enough so that it can be carried around.
Make a dynamometer to detect small currents. Cut the bottom 1 cm from a styrofoam coffee cup. Put a small inexpensive compass in the bottom section. Make 20 to 30 wraps of 24 gauge or 28 gauge insulated wire around the cup base so that the wire goes across the open end of the cup. Leave about 30 cm of each end of the wire loose, to make connections to the power source. Strip the last 2 cm of each loose end so that electrical connections can be made to a straightened paper clip.
Turn the top part of the styrofoam cup upside down. Place the base of the cup (open side up so that the compass is visible) on top of this base.

Test the dynamometer by holding one paper clip on the positive terminal of a battery and then touching the other clip very briefly to the negative terminal. What happens to the compass needle when the second clip touches the terminal? What happens if the first clip is held on the negative terminal and the second clip is touched to the positive?

Insert one paper clip into a potato. Watch the compass needle to see what happens when the second paper clip is jabbed into the potato. Remove the second clip and jab in again, observing the compass needle as you do this.

Connect two potatoes with a straightened paper clip. Put the first clip into potato 1 and the second clip into the other potato. What happens? Try substituting a lemon, an orange, an apple, a green tomato, a red tomato, a cucumber, and a carrot for the potato(s).
Obtain 70 cm, 1 m, 3 m, 4.5 m, and 6 m lengths of insulated wire and five 10 cm to 15 cm long 5 mm bolts. (It can be done with one bolt if the wire is removed and the next length wrapped on after each trial.) A 6 volt battery is best for this activity, although 1.5 volt dry cells may be used. The 1.5 volt cells may run down quickly when used as power sources for electromagnets.

Wrap one length of wire around each bolt, leaving 25 cm of each end of the wire to make connections to the battery. With the lengths of wire suggested, 20 cm, 50 cm, 2.5 m, 4 m and 5.5 m will be the length of wrap forming the electromagnet. Connect the free ends of the wire to the battery, and record the strength of the magnet produced by the number of straight pins or paper clips the magnet will hold. Graph the results of the investigation. Predict how many clips could be picked up with 7.5 m or 10 m of wire.
Some fax machine paper is thermal paper, sensitive to heat. Use the roll ends of such fax paper as a heat indicator. Does the paper change gradually with increasing heat or is the change very quick at some particular temperature? Lay a 10 cm piece of nichrome wire and a 10 cm piece of copper wire nichrome and copper wires across a piece of the paper, so that the wire is in constant contact with the paper. Use tape to hold the wire in contact with the paper if necessary. Apply a current to each wire and observe the effects on the paper. What uses are made of nichrome wire and copper wire?
What other uses can you think of for the heat sensitive fax paper?
Design and construct an alarm system which will detect whether a door, window or a lunch box is being opened. The alarm may be audible, visible, or both. It should use a 9 volt battery as a power source.
Collect some old radios, toasters, electric mixers, and other small appliances. Distribute these for the students to dissemble in the laboratory. Ask them to produce a poster or set of diagram to explain how the appliance works. Take the components and reassemble them in a line which indicates the sequence of electrical flow through the device. Caution students not to plug the appliances in at any time. The external part of the power supply cords might be cut off to discourage this. Do not use old television sets for this activity. The picture tube may implode, showering the class with glass fragments.

Note: Many of the resources listed in Science: An Information Bulletin for the Middle Level - Key Resource Correlations describe activities or ideas for activities.