Teacher's Guide Grade 4: Electrical Circuits

Teacher’s Guide Grade 4: Electrical Circuits

TEKS 4.6 Force, Motion, and Energy: The student knows that electricity exists in many forms and can be observed in cycles, patterns, and systems. The student is expected to:

C) demonstrate that electricity travels in a closed path, creating an electrical circuit, and explore an electromagnetic field.

Background Information: This unit focuses on electricity as a form of energy that is used to do work. Students are introduced to static and current electricity. They learn that there are two types of electrical charges - positive and negative - that behave like the poles of a magnet.

Students discover that electric current can only travel in a closed path, called an electric circuit, and they learn about the components of a simple circuit which consists of: a power source, like a battery a closed pathway made of an electrical conductor, such as copper wiring and an object that does work, such as a light bulb

Students apply their knowledge of electrical conductors and insulators as they investigate what constitutes an open and a closed circuit. They learn about the electromagnetic field that forms around a conductor when current flows through it, and they discover how an electric circuit can be used to create a temporary magnet called an electromagnet. They also learn how magnets can be used to generate electricity when a conductor is moved within a magnetic field in a simple generator.

Prerequisite Knowledge: Prior to this year, students learned that energy, force and motion are related and are a part of their everyday lives. They have used their senses and simple tools to explore different forms of energy, including thermal/heat, light, sound and mechanical energy, but not electricity. They have also investigated how increasing or decreasing the amount of light, heat and sound energy affects matter.

In addition, students have observed forces, such as magnetism and gravity, acting on objects. They are familiar with how magnets are used in everyday life. However, their experience with magnets is limited to permanent

magnets, but this experience will provide some background knowledge of the behavior of magnets that can be applied to electromagnets which are introduced this year.

Common Misconceptions: Students may think that in an open circuit, electric current flows to the place in the circuit where there is a break, and then “turns back” to the battery when it cannot flow through the break. It is important for students to understand that in an open circuit current does not flow at all. Electricity can only travel in a closed path.

Electrical safety is paramount, and students need to understand that the current that flows from an outlet is dangerous because it is much stronger than the current produced by a battery.

Essential Questions:

1) What is electricity and how is it used?

Electricity is a form of energy. There are two types of electricity, static and current. Static electricity, such as lightning, does not need a circuit to flow through. Current electricity must have a closed pathway, formed by an electrical conductor, in order to flow. Electricity is used to do work by being transformed into other types of energy, such as heat, light, sound or mechanical energy, when it flows through objects that are designed to operate using electric current.

2) Where does the energy in an electric circuit come from?

The energy in an electric circuit comes from a power source, such as a battery. The battery stores energy in the form of chemicals, and this energy is released to do work, such as light a bulb or make a bell ring, when the circuit is closed.

3) What is the difference between electrical conductors and insulators, and how are they used in an electric circuit?

An electrical conductor is a material that allows electricity to flow through it. An electrical insulator is a material that does not allow electricity to flow through it. Both conductors and insulators are used in electric circuits. Electrical conductors, such as copper wiring, form the pathway through which electric current flows, while electrical insulators, such as the rubber coating that covers the wire, keeps the electric current within the desired pathway.

4) What is a magnetic field?

A magnetic field is the area that surrounds a magnet and where the force of magnetism is observed. It emerges from the north pole and reenters through the south pole of the magnet. Both a permanent magnet and a temporary electromagnet have a north and a south pole that produce a magnetic field. The difference is that the poles of an electromagnet and the direction of its magnetic field can be switched by switching the terminals the coiled circuit wire is connected to.

5) How can an electromagnet’s magnetic force be strengthened?

The strength of an electromagnet depends on the force of the current and the number of wire coils that form the circuit. By increasing the number of coils, or by using a stronger battery the strength of the electromagnetic field can be increased.

6) How can magnetism be used to produce electricity?

Electricity can be generated by moving a conductor, such as a wire coil, through a magnetic field. When the coil of wire is spun within a magnetic field, negative charges move through the conductor producing an electric current.

7) What is needed to create a simple closed circuit?

A simple closed circuit consists of a power source, such as a battery, a pathway for the electric current to flow through, usually formed by wire, and an object designed to do work using electric current, such as a light bulb. The conductor forming the circuit must connect one terminal of the battery to the other terminal while forcing the electric current to flow through the object doing the work. It may or may not contain a switch which simply makes it easier to open and close the circuit at will.

Notes: