Time: 25 minutes
Materials (per pair):
D-cell battery (preferably mercury free)
Rubber band
2 strips aluminum foil or insulated copper wire (5-6”)
Pencil
Flashlight bulb
Masking tape
Paper
Safety Considerations
 The voltage of 1, 2, or even 3 D-cell batteries is not enough to be dangerous.
However, the amount of electricity in an electric wall outlet can be dangerous and should not be used for experimentation.
 If copper wires are used, warn the students to be careful not to poke themselves or anyone else with the sharp ends.
 Remind students to handle bulbs with care.
 Short circuits can be caused by connecting the positive terminal of the battery directly to the negative terminal without a bulb in the path. If the students create a short circuit, the foil or wire may get warm. It is unlikely that the foil or wire will get too hot, but be aware of this. Aluminum foil will not get as warm as a copper wire.
 IMMEDIATELY discard batteries that are leaking. Dispose properly, following instructions on label.
Directions
Please practice with the circuits ahead of time!
1.
Make sure students are sitting at tables and not on the floor.
2.
Instruct the students to form pairs or groups of three (for large groups, everyone should be in a group of three since materials are limited).
3.
Pass out materials or have one person from each group come up to get a set.
4.
Tell the students to look at the battery and compare both ends. They should notice one end is labeled with a negative (-) and one is labeled with a positive (+).
5.
Ask them to identify the negative and positive terminals, and ask them which end has the most electrons. *The negative terminal has the most electrons.*
6.
Let the students experiment with their supplies to try to get the lightbulb to light up.
Remind them to draw or sketch the circuits they test. Challenge the students to find out how many different ways they can build a complete circuit.

Helpful Hints
 The circuits must be complete (the connected parts must connect from one end of the battery to the other). If the path is broken or interrupted, the circuit will be broken and the light will not light up.
 If students are having trouble holding the connections suggest using tape on to hold the ends of the foil or wire in place.
 To make a good connection the foil strip should be wrapped around the bulb base, leaving enough foil to connect to the battery ends.
More Challenges
 In a series circuit, there is only one path for the electrons to follow. Connecting two light bulbs in the same circuit, but with the same number of batteries, will cause each bulb to burn more dimly than if the circuit contained only one bulb because the current must be shared by the bulbs.
 In a parallel circuit, the electrons have more than one path in which they can travel.
The enables both bulbs to burn brightly as they would if there were only one bulb in the circuit. Another advantage of parallel circuits is that if one bulb burns out, the other bulb won’t be affected because there is still a complete circuit.

Discussion
Q: What do you think happens when on bulb in a string of Christmas lights is defective?
A: Somewhere along the circuit path, there is a break that interrupts the flow of current.
In some types of lights, if a bulb burns out, the break in the bulbs filament interrupts the path. Lights wired this way have a series of circuits. Other types of lights are designed with circuits that bypass or go around individual light bulbs so that the circuit is not broken if a bulb burns out. This type of circuit is called a parallel circuit.
Q: Compare the circuits that caused the bulb to light up with the ones that didn’t. How are they alike? How are they different?
A: There are many possible answers. The circuits that work will have an unbroken path for the flow of electrons between the positive and negative ends of the batteries.
Q: Why do you think the other circuits did not cause the bulb to light up?
A: Because the circuit path was broken somewhere, interrupting the flow of electrons and preventing them from reaching the other end of the battery.
Frequently Asked Questions:
Q: Why do batteries die?
A: After a while, the chemical reactions inside the battery that cause electrons to move away from atoms, leaving those atoms positively charged, no longer happen or the battery can no longer keep the negative and positive charges inside the battery apart.
Without a difference in electrical pressure or potential between the two ends of the battery, there can be no voltage.
Q: What does the number of volts on a battery mean?
A: The voltage on the battery limits the amount of currency that the battery can produce. Batteries, such as A, AA, C and D carry 1.5 volts. Additional voltage can be obtained by connecting multiple batteries together. For example, flashlights require 2 batteries to power a 3-volt bulb. Batteries such as the type commonly used in smoke detectors supply 9 volts from a single battery.
Q: Why are batteries different sizes?
A: Different sized batteries contain different amounts of chemicals. Since larger batteries, such as D-cell batteries, contain more chemicals than an AA-size battery of the same type, they can deliver currents for longer times. Larger batteries can keep the chemical reactions going longer with the continuous demand for current that some devices require to work.