Hi Steve,
You're right about wanting to have "easy to grasp" stuff.
Most people, let-lone kids, have trouble coming to terms with just how big this place is and the forces it can generate.
Here are some things I say to the uninitiated to "come to terms":
*speed of light = 300,000km/h (Yeah, I know it's a little less, but really!!) (oops, that should read
300,000km/sec!)
*this equals the distance from the earth to the moon (see above), ie, light takes one second to travel this distance.
*eight minutes from the sun to us on earth.
*4.3 years to Alpha Centuri
*300,000 years to span the diameter of our galaxy, the Milky Way
Most people cease after these numbers.
As to the forces around us:
*nuclear fusion powers the sun, simple physics with e=m*c(square), and the sun's power is an application of this equation. The potential energy in a grain of sand if converted to energy would vaporise Sydney. Take it from there.
This hobby is wonderful, where it allows you to take it to the level that you want. Enjoy it. Enjoy it with others,
.