Traditionally children have been given mythical explanations for thunder and lightning. Examples include God moving furniture; Thor with his hammer; even a giant flapping bird. Giving scientific explanations is possible, even with young children. Keep explanations simple and demonstrable. Illustrate aspects of thunder and lightning production through simple experiments. Children will enjoy the experiments and through this process move beyond fear towards understanding.
Explain that lightening is a giant electrical spark. Ask children whether they have seen sparks or heard crackling static electricity when they pull off a sweater or brush their hair.
Demonstrate by getting the children to shuffle along carpet in their socks. Have them touch something metal, or another person, then ask if they felt a spark.
Explain the spark is due to the build-up of positive and negative charges. Describe how a cloud is made up of tiny particles of water and ice, jostling against each other. As they rub each other they create an electrical charge, just like when their feet rubbed against the carpet.
Teach that positive particles rise to the top of the cloud while the bottom particles become negative. High points on the ground also gain a positive charge, attracted to the negativity in the cloud above. Indicate that opposites attract: positive and negative charges will try to meet. Lightning jumps from the negative cloud bottom to the positive top; occasionally from negative cloud to positive ground. Completing an electric circuit this produces light energy---similar to turning on a giant flashlight.
Demonstrate by showing the battery's positive and negative poles, the flashlight's connectors and switch. Ask them to press the switch and complete the circuit--the bulb will light up.
Explain that lightning strikes cut channels through the air, producing shock waves. Collapsing inward to fill this channel, the air makes a clap of sound we call thunder.
Inflate the lunch bag by blowing. Hold the neck tightly to seal.
Ask a child to slap the bag hard between his hands. Listen to the bang as the bag deflates.
Explain that we see lightning before hearing thunder because light travels faster than sound. Teach that we can tell how far away storms are by how long it takes for thunder to reach us.
Next time there is a storm, give children the stop watch. Ask them to start it when they see lightning and stop when they hear thunder.
Divide the number of seconds between flash and rumble by five to find how many miles away the lightning flashed.
Further demonstrate how opposite charges attract by asking children to rub an inflated balloon on their hair or sweater. The now negatively charged balloon will stick to the wall or cause hair to stand on end. For older children, make lightning using an aluminium pie plate and a styrofoam plate or cup. Charge the styrofoam by rubbing. Using a pencil as a handle, place the aluminium plate on the styrofoam. Touching the aluminium should produce a small shock, and with lights out, a visible spark.