Layers of the Earth: A Classroom Activity

Photo by NASA

Photo by NASA

From the core to the crust, the Earth is a pretty big deal. It has a diameter of about 6,400 km, and it is made of various layers that help change the surface of the earth. These layers are defined by either what they are made of or how they move. When we look at the chemical composition of each layer, we are defining them as compositional layers. The compositional layers are the crust, the mantle and the core. When we look at the mechanical properties of the layers, we are defining them as the mechanical layers. The five mechanical layers are the lithosphere, the asthenosphere, the mesosphere, the inner core and the outer core. Although we only see the outermost layer of the earth, we have learned a lot about the layers underneath by looking at seismic waves and various rocks at the surface. 

The three compositional layers of the earth are defined by significant changes in chemical composition. The outermost layer is the crust. It is the thinnest layer making up only about 1 percent of the earth. The crust is mostly made of elements like silicon (Si), aluminum (Al), potassium (K), calcium (Ca), oxygen (O), sodium (Na) and minerals made of these elements. The crust can be subdivided into two types – oceanic crust and continental crust. Oceanic crust tends to be thinner (approx. 5-10km thick) than continental crust and younger too! Continental crust is on average 30 km thick, and contains the oldest rocks and minerals. Both types of crust cover the entire outer portion of the earth. Below the crust lies the mantle (approximately 2,890 km thick.) The mantle is made of silicon (Si) and oxygen (O) like the crust, but it also contains large amounts of iron (Fe) and magnesium (Mg). The final compositional layer of the earth is the core (approx.3,480 km thick). The core is made of iron (Fe) and nickel (Ni). It is under intense pressure and high temperatures, and it is the densest layer of the earth. Although these layers may share common elements, the contents differ enough to create the distinct layers.

The five mechanical layers of the earth are defined by how the layers move. The layers can be described as rigid, plastic or liquid in consistency. The outermost mechanical layer is the lithosphere. The lithosphere is rigid, and it includes the crust and the uppermost part of the mantle. The lithosphere is divided into the tectonic plates, areas of continental crust and/or oceanic crust that move and shift over time. The tectonic plates of the lithosphere move and shift on the plastic layer called the asthenosphere. The asthenosphere is under more pressure than the lithosphere and has a higher temperature. It is considered plastic because the rock has the ability to flow more than a rigid layer, but not as easily as a liquid layer.  The rock in the asthenosphere could melt if exposed to the surface, but it is under extreme pressure causing it to flow like a plastic. The mesosphere is the layer below the asthenosphere. The mesosphere is hotter than the asthenosphere, but it is rigid because it is experiencing more pressure than the layers above. The last mechanical layers of the earth are found in the core. The core is split into the outer core and the inner core because the two layers differ in rigidity. The outer core is liquid iron (Fe) and nickel (Ni). The flow of the outer core creates and sustains the earth’s magnetic field. Unlike the outer core, the inner core is solid. The inner core is made from mostly iron (Fe), but it can also contain nickel (Ni) and traces of precious elements like gold (Au). It is extremely hot, and under extreme pressure from the layers of the earth and atmosphere around it. All of these layers work together to make our dynamic earth!

Create a foldable Earth with the activity below to teach students about the various layers of the earth. To learn how the asthenosphere moves tectonic plates or learn about the natural disasters caused by that movement, check out our new Earth Science on Wheels topic Dynamic Earth!

final product edit

This project models two different ways to understand the layers of the earth. It addresses the compositional layers of the earth, and the mechanical layers of the earth.

Materials:

all the supplies edit

Procedure:

  1. Pass out template to each student.
  2. Instruct students to cut out the Earth. Once they have cut the outside, tell them to cut along the dashed line that says “cut here.”
  3. Next, fold along the “Fold line.” Then, set the Earth aside.
  4. Now, tell students to cut out the quarter circle labeled A. This will represent the mechanical layers of the earth.
  5. Invite students to color each of the areas in the quarter circle a different color starting from the inside:
    1. Yellow – inner corre
    2. Orange – outer core
    3. Red – mesosphere
    4. Pink – asthenosphere
    5. Purple – lithospherecut and colored edit
  6. Have students set aside the mechanical layers (A.) for now
  7. Instruct students to cut out the second quarter circle (B.) from the template sheet. These will represent the compositional layers of the earth. Invite students to color each of the sections a different color:
    1. Yellow – core
    2. Red – mantle
    3. Brown – crust
  8. Have students set aside the compositional layers (B.) for now
  9. Instruct students to glue the earth, to the background paper. Remind them to not glue down the flap.
  10. Tell students to place the mechanical layers (A.) on the background paper underneath the flap and glue it to the paper.
  11. They should then take the quarter circle that represents the compositional layers (B.), and place it on the backside of the flap of the Earth. Then, carefully glue it to the back of the flap.
  12. Once completed, show students how to flip up the flap and see the mechanical layers on the background page and the compositional layers on the back of the flap. Students can add notes to the layers to help them learn what the layers do!

Educator How-To: Making the Moon out of Cheese (and Crackers!)

After months of renovation, the Burke Baker Planetarium at the Houston Museum of Natural Science will re-open March 11 with the best picture of the universe in the world! The Evans and Sutherland Digistar 5 digital projection system boasts the first True 8K image on the planet, with twice the resolution as an IMAX theater. The powerful digital software can zoom audiences to distant stars to see the universe from infinite perspectives, not just from the surface of the Earth. And with a tilted, seamless dome overhead and updated, comfortable seating below, the planetarium will be a must-see for Houston residents and visitors from literally anywhere.

But while it’s closed, life goes on, and without the incredible demonstration available at the planetarium to show the phases of the moon, explaining the orbit of our only satellite to kids (and keeping their attentions) can be a difficult task. So for hungry minds and bellies, we’ve got something to tide you over until the doors to the planetarium open once again.

Teach your students about the phases of the moon with this awesome Solar System snacking activity! I created this lesson plan as an alternative to the Oreo™ phases of the moon activity that we think is so clever. This science snack is a healthier alternative and will satisfy hungry students without the sugar rush. Educator How-To: Making the Moon out of Cheese (and Crackers!)

Moon worksheet

Materials:

  • Ritz™ Crackers
  • American cheese slices
  • 1.5 inch round “cookie” cutter
  • Phases of the moon chart
  • Phases of the Moon worksheet
  • Markers
  • Waxed paper
  • Plastic knives

Educator How-To: Making the Moon out of Cheese (and Crackers!)

Moon phases

Procedure:

  1. Give each child a copy of the phases of the moon chart.  Go over the different phases, and consider using our Educator How-To: We’ll See You on the Dark (and Light and Far) Side of the Moon to demonstrate the phases in an active, hands-on fashion.
  2. Distribute one slice of American cheese to each student.
  3. Instruct students to carefully use the circular cutter to cut four circles from the cheese. With careful placement, one slice of cheese will be sufficient.
  4. Using a plastic knife, students will then cut one circle of cheese in half.
  5. The second circle will be cut using the circular “cookie” cutter.  Place the cutter carefully on the circle of cheese so that a crescent-shaped piece of cheese is cut from one side.
  6. The same procedure should be used to cut an additional crescent-shaped piece from the third circle of cheese.
  7. The fourth circle will remain whole.
  8. Now you are ready to go! Distribute the Phases of the Moon worksheets and have students place a Ritz™ cracker on each “moon.”
  9. Students will now arrange the cheese on the crackers to reflect each phase of the moon.
  10. When finished, students may eat the tasty moon snack!

HOW TO: Solve the Mystery of the Mobius

Every now and then I get a little bit obsessed thinking about things that I know exist but are very strange in such a way that I halfway don’t want to believe they can exist… like the Mobius Strip! The definition for the Mobius Strip on Dictionary.com is “a continuous, one-sided surface formed by twisting one end of a rectangular strip through 180 degrees about the longitudinal axis of the strip and attaching this end to the other”. — OK, so that is a bit difficult to follow but how about “a surface with one side and one edge”?

So now you’re saying “Wait — how did that rectangle become something with only one edge? I am quite sure that rectangles have FOUR edges!” and you would be right – but the mystery of the Mobius Strip lies in that little half twist of the rectangle – and once you have your Mobius Strip in your hand you can see how wonderful they are! I am going to give you some instructions on how to make your own Mobius Strip that I found on this website– I think they are pretty simple to follow but I’ll include some other cool Mobius related links below!  

So – let’s make one:

To construct a Mobius Strip requires only a piece of paper, scissors, and some tape.

Simply cut the paper into a single, fairly long strip. Now, holding each end of this strip, give it a half twist (be sure not to give it a whole twist – just flip one of the ends around so that the sides are facing the opposite direction). Now, all that is left is to do is to attach the two ends together into a loop with the tape.

Here are some photos to help you with the first steps:

So as you make the simple Mobius Strip remember you just want to add one half twist to expose the other side of your rectangle. I added letters on the ends to show you how it should be taped together.

So now what? Do you have a single sided surface with only one edge? Let’s check!

Start with a marker and draw a line down the middle of the loop – I started between the letters on the seam so I would be able to easily find my starting point. As you draw your line you will turn the loop around and around and realize that you come back to exactly the same place — ONE SIDE! If you follow the edge around with your fingertip you can also discover how this has only one edge… amazing isn’t it!?

For those of you who like to know the real life application for things that seem incredible and possibly otherwise worthless this is useful for typewriter ribbons and conveyor belts to help keep the wear evenly distributed rather than a regular looped belt without a twist that would have to be flipped periodically to allow for consistent wear.

Ok, next let’s see what happens when you cut along your line in the middle of the Mobius Strip. I’m not going to tell you what happens next but I promise it is pretty cool and you should try it. Then – see what happens if you were to cut half way between your midline and the edge, what happens if you take the result of your first cut and try to cut it in half again, what happens if you put two half twists in your first Mobius Strip and then cut it!? There are lots of fun things to try… what can you come up with?

Check out these links on Mobius related info:

knit a mobius scarf

make a neverending comic or draw your own!?

UC Berkley had a “Build a twisted bridge” challenge!

A bit more about the Math behind the Mobius strip

If you like the Mobius Strip – you’ll love the Klein Bottle!  if you know someone who’s particularly interested in topology and mysterious math you can actually buy a Klein bottle and there’s still time to get it before the holidays!

Have fun!