Have you ever been in the middle of playing with a battery-powered toy, when you noticed it beginning to move very slowly or not at all? Have you been using a calculator that simple stopped working? What happened to the power of the battery? Could you predict how long this would take to occur?

In your class you may have been making bulbs light with D-cells. As you know, there are other kinds of batteries. For example, a remote control for a television may use a 2 AAA-cells, while a portable stereo may use 2 D-cells. How are these cells different? How are they the same?

Today you will use a multimeter to measure whether and how quickly the electric current in different kinds of cells gets used up.

Discuss the following questions with students in your group. Write down your ideas and be prepared to present them to the class. Be sure to include the reasons behind your thinking.

You've noticed that each of your electric cells is rated at 1.5 volts. Use the multimeter to confirm the accuracy of the voltage rating.

What do you think will happen if you connected each of these cells in the same circuit for 30 minutes? What makes you think this will happen?

After you've had a chance to discuss your ideas with your class, go to "Investigating the Question" to try it out.