As we have previously discussed the formation of the solar system and Earth, I wanted to take it a little farther and teach Joey about the composition of Earth, specifically about what lies underneath Earth’s surface, or crust. I explained to Joey that he would be learning about the various layers of the Earth, how thick each of these layers are, their temperatures, etc.
J: YOU KNOW THIS ONE IS TOO BORING.
I saw the Joey was a little distracted and reluctant to give this lesson his complete attention. While I had planned out specific questions to the material that we were going to cover, I decided to abandon that route and figure out a way to make this lesson interesting for Joey. I reminded Joey about how he always likes to play word association games, and his face lit up. Now that I had his full attention I explained to him that I would simply read sections of the lesson to him, and that he could write creatively about whatever popped into his head after listening to this information about what lies beneath Earth’s outer surface, and if what he wrote applies to his life in any way, all the better.
J: YOU RULE TO CHANGE IT LIKE THAT.
Jumping right into the lesson, I told Joey that the layer directly below Earth’s crust is called the mantle, which is close to 1,800 miles thick. Due to great heat and pressure, while the inner part of the mantle is predominantly solid, it can flow slowly, like warm clay or Silly Putty.
J: THIS REMINDS ME OF THE TIME I ATE SO MUCH PIZZA CRUST THAT MY STOMACH STRETCHED SO FULL THAT MY MANTLE, THE MIDDLE LAYER JUST BELOW MY SURFACE, REALLY FELT LIKE IT EXPANDED TO EIGHTEEN HUNDRED MILES THICK.
At this point I showed Joey a diagram of the layers of Earth, and just how much of the planet is made up of the mantle.
J: WOW I MUST HAVE EATEN SO MUCH PIZZA CRUST THAT DAY.
In comparison to the inner area, the uppermost part of the mantle is cooler and more brittle. So in many ways, the upper mantle behaves in a similar way to the overlying crust of Earth. Together, the crust and the uppermost mantle form a rigid layer of rock called the lithosphere, from lithos, the Greek word for stone.
J: THE LITHOSPHERE MAINLY REMINDS ME OF SOME CRISPY CHEESE THAT TURNS BRITTLE AND BLACK WHEN IT IS LEFT IN THE OVEN TOO LONG WITHOUT LISTENING TO THE SOUND OF SIZZLING THAT A PIE MAKES SIGNALING THAT IT IS READY FOR CONSUMPTION.
Below the mantle lies Earth’s core. The core is close to twice as dense as the mantle, and is made up almost entirely of metals such as iron and nickel. The core consists of two distinct parts, 1,400 miles of liquid outer core and 745 miles of solid inner core.
J: THE EARTH IS TOO THICK, EXACTLY LIKE THIS DEEP DISH PIE I ATE ONCE. THE CORE OF MY HUNGRY STOMACH WAS SATISFIED WITH EVERY BITE.
Lastly, I explained that the high temperatures in the outer core melt the iron and nickel, but the extreme pressure of the inner core squeezes them solid, even as the temperature soars over 6,700 degrees celsius, which is comparable to how hot it is on the surface of the sun.
Joey was quite distracted with the thought of eating pizza at this point, and chose to focus more on that than the lesson during his final comment.
J: THIS LESSON HAS MADE ME SO TREMENDOUSLY HUNGRY. THIS LESSON HAS HARVESTED MY INNER MOST DESIRE TO EAT SOME STEAMING-WITH-FLAVOR PIZZA!