Activity One: Introduction to Earth’s Layers
Objective: Make observations (firsthand or from media) to collect data that can be used to make comparisons.
Materials: read-aloud book - The Street Beneath My Feet, copies of earth labeling activity, pencils scissors, glue.
Begin the unit by reading The Street Beneath My Feet by Charlotte Guillain and Yuval Zommer.. This will introduce the unit with a fundamental foundation of geology, recognizing that earth is made up of many layers of different materials. The book contains an extensive fold-out section that provides a visual of what is happening from where we are standing all the way to the center of the planet.
Introduce the by showing the video, Layers of the Earth for Kids | Learn facts about the different layers of Earth or one similar. This eight-minute video shows students each of the layers beneath our feet and teaches the correct terms and vocabulary.
In our Layers of the Earth for Kids video, the students will discover some facts about the four main layers that make up our Earth. The Earth is not simply a giant ball of dirt, rocks, and minerals. On the contrary, our planet is much more than meets the eye. The crust is the outer layer of the earth and is mostly between 5 and 40 km thick depending on where you are. Under the oceans, it is only about 5 to 8 km thick, and we refer to these areas as oceanic crust. The crust beneath tall mountain ranges reaches up to 80 km thick. We refer to these parts as continental crust. The temperatures of the earth's crust can range anywhere between air temperature and 900°C, which is hot enough to melt rocks! This thin layer consists of broken pieces called plates, which float on top of the soft mantle layer below. (The movement of these plates is what often causes earthquakes.)
The mantle layer is the largest at about 2900 km thick. It comprises extremely hot, dense rock that flows like asphalt. The temperature at the top is about 900°C, but it's about 4000°C at the bottom! This layer is entirely solid except for very small zones that have melted due to excess heat, reduced pressure, or unusual chemistry. In those places, the melted rock escapes to the earth's surface, creating volcanoes. Then comes the outer core of the earth. The outer core consists mostly of melted nickel and iron. This layer lies around 2900 km below the earth's surface and is around 2200 km thick. The temperature ranges from 4000°C to 5000°C! The inner core is about 1200 km thick with about 5000°C temperature. There is so much pressure in the core that the metals squeeze very tightly, forcing them to vibrate as solids do. This pressure comes from the weight of the other layers that press down on it.
Activity Two: Hard-Boiled Egg Dissection
Objective: The students will practice how scientists use models to visualize what may be difficult to see or understand and learn how models have limitations
Materials: hard-boiled eggs, trays, plastic knives
Overarching questions to continue to consider are: ‘What is under our feet?’ and ‘How do rocks and the earth change?’ In this particular lesson, students grapple with the question, ‘Could I dig through the earth?’ The dissection gives the Kindergarteners a hands-on way to experience the layers of the earth. They practice how scientists use models to visualize what may be difficult to see or understand and learn how models have limitations.
In this dissection, students will use a hard-boiled egg to model the layers of the earth. They work with a partner to crack the shell and peel a thin layer representing the earth's crust. Students should notice that the shell was solid, like the earth's crust, and relatively thin compared to the rest of the egg. It also broke into pieces, just like tectonic plates. They will then work to separate the white from the egg's yolk, representing the earth's mantle and core.
Be sure to discuss the limitations of this model and point out that while the white of the egg can easily be squeezed by human hands, the real mantle of the earth only deforms very slowly (rates that fingernails grow) and from tremendous forces. Following this science experiment, ask the students, "What other objects or food could represent the layers of the earth?" This part of the activity is where Kindergarteners can transfer the idea of models and the layers of the earth to a different example, such as a peach, an avocado, or even a dragon fruit to represent the Earth.
An additional example of scientists relying on models would be to use a raw egg held up to a student’s ear. This activity is best done with the teacher holding the egg. Once the egg is placed, tap on the outer end and have the students notice if they hear anything from inside the egg. The sound waves that move through the egg give scientists some idea of what is inside. Tell the students the tapping is moving things inside just as an earthquake moves things inside our Earth.
Activity Three: Model of the Layers of the Earth – Example One
Objective: The students will use playdough to design and build a structure of the Earth’s layers.
Materials: ingredients for homemade playdough, wooden spoon, hot plate, potholders, plastic or latex gloves for students, plastic knife, toothpicks, small post-it notes, (purchased playdough or clay)
For this activity, cook up a batch of homemade playdough and divide the dough to make six different colors: blue, green, red, orange, yellow, and brown.
Students: To make the dough, add the following ingredients to a pot:
- 3 cups of flour
- 1/2 cup of salt
- 6 tablespoons cream of tartar
- 3 tablespoons of vegetable oil
- 3 cups of water
Students: Mix until all the lumps are gone.
Teacher: Move the pot to the hot plate, and cook over low heat, stirring often. The dough started to thicken in a few minutes. Once the batch starts pulling away from the sides (but is still a little sticky), turn off the heat and allow it to cool in the pot. Once cool, the stickiness will disappear, and the dough can be kneaded and dyed.
Divide the cooked playdough into six parts: two small (golf ball-sized), two medium, and two large balls. Drop several drops of food coloring into each ball. The two small balls become red and green, the medium balls are dyed orange and brown, and the large ones are dyed yellow and blue.
This batch will make enough dough for two groups to complete the project. Depending on the number of groups, cook up a few more batches. Be sure to do this step with the students.
Alternatively, purchased playdough or molding clay can be used for this project.
Building the Layers of Earth
Now it was time to create the layers of the earth. Start by rolling the small red dough into a ball. This serves as the Earth’s solid inner core, which is almost as hot as the sun.
For the next layer, flatten the medium-sized orange dough and place it around the red ball. Pinch the sides closed, removing any extra dough in the process. This layer is the liquid outer core that spins creating Earth’s magnetic field.
Next, flatten the large yellow ball to create the mantle. This is the thickest layer and is made of very, very hot rocks.
Flatten the medium brown ball and place it over the yellow ball. The thin brown layer represents Earth’s crust and is made up of cold, brittle rocks.
Finally, flatten the blue ball and cover the earth in the ocean. Form the continents, (the land we walk on) using the small green ball of dough and place them on the blue layer to create the globe.
The final step – cutting the planet in two. The easiest way to do this is to use dental floss. This will expose the layers from the crust to the core. Using toothpicks and small post-it notes, label the layers.
Activity Four: Model of the Layers of the Earth – Example Two
Objective: The students will use a variety of materials to design and build a structure of the Earth’s layers.
Materials: plastic champagne-style cone-shaped glasses– one for each student, orange and yellow colored sand, stones of various sizes, red playdough, soil, blue clay, green leaves, dried leaves, twigs, trays and/or bowls for sorting materials, scoops and spoons, masking tape or painter’s tape, image of layers of the Earth
Sequence of layering, bottom to top:
Red playdough
Orange sand
Yellow sand
Brown material
Blue clay
Green material
Create a model for students to use as an example. Prepare materials and divide them across tables for groups to share. As this is a step-by-step project, have students follow the directions as they are given.
- First, place a ball of red playdough in the bottle of the jar and flatten it out. This represents the inner core.
- Next, pour a layer of orange sand to about an inch deep. This represents the outer core.
- Now, pour a layer of yellow sand to about two inches thick. This is the mantle of hot solid rock.
- Brown soil mixed with twigs represents the crust.
- Flatten a piece of blue clay to represent oceans.
- Finally green material to represent to land.
Substitutions for the representative materials are certainly possible. Consider colored rice, a mixture of slime (cornstarch and water) of various colors, and a variety of craft materials. Depending on the shape and size of the jars, gather enough supplies to ensure all students can create each layer.
Using the masking tape or painter’s tape, help students mark each layer on the outside of the jar. The labels can be prewritten or printed on address-type labels.
