My six-year-old, Cassandra, knows what lightning is and what causes it. It is ironic is that when I was teaching high school science in a Christian school, I could not get ninth-graders to understand or even care what lightning is and why it makes thunder.
In explaining to Cassie, I had to explain about electrical currents and their need for a conductor. I showed her a diagram of a light switch and showed her that if the road is broken, the electrons cannot travel on it.
I told her that electricity likes to go through certain kinds of materials which have electrons available to travel. Some electrons are very happy where they are and are not available to go on an electrical adventure. Other electrons are not content where they are and are ready to move out and make some electricity happen! Copper wire is full of electrons that are ready to travel. So does salt water. Hey, you are made of salt water. That is why you must be careful about electricity. Electricity likes to travel through human bodies.
I also explained that negative charges and positive charges do not like to be separated. They want to join together like a bunch of teenage girls and a bunch of teenage boys. In a thundercloud, there is a massive charge on the ground and another massive charge in the cloud.
Electricity likes to travel in a wire, but if it has to, it will travel through the air. If the charge is powerful enough, it will force its way through the air. This makes the air so hot that the expanding air molecules hit each other. To understand this, she needed to know that increased thermal energy makes matter expand. I showed her a broken egg that expanded in boiling water. She understands.
"So the loud sound is the air molecules getting bigger?"
"You almost got it. Actually, it is the sound of air molecules moving away from each other in a big hurry and hitting each other as they move. The actual molecules stay the same size, but when air gets hot, the molecules want to be farther apart from each other. So they have to move apart and this is a violent process. The air surrounding a lightning strike is so hot that it is hotter than the surface of the sun. These molecules are forced to participate in an electrical current and neither the air or the electricity likes this arrangement. So they complain about it."
Cassie asked this question at 10:10 pm. School happens when learning happens. Cassie knows about electrical currents, circuits, arrangement of electrons in atoms, and thermal energy. She knows that heat is the exchange of thermal energy and that heat makes things expand, even air.
She know more about meteorology than many high school students. She is six. This is the power of delight-centered learning--she will remember that which she was interested in, not that which she was coerced into learning. That is it right there: She asked the question and so she retained the answer and the whole process opened doors to learn and understand a whole lot more.
Next time we have a science conversation, I will be able to say, "Remember how matter expands when it gets warmer?"
"And you remember that it is not because the molecules expand, but they move away from each other and this makes matter expand."
"Yeah, I remember."
I'll tell you what--we can move right along from there!
I teach science and history in our family home school. I mostly use a "lecture series" strategy. The kids read text books and other science books, but they really respond when they ask a question and are prepared to listen to the answer. Precept upon precept, we build their understanding of how the world works.