LESSON 3 What is the Composition of Earth’s Surface?

ACTIVITY 3.1: THE THEORY OF PLATE TECTONICS The plates are made of two different types of igneous rock. (Oceanic basins are basalt; continents are mostly granite.) The plates move slowly and continuously as rigid block Plates as huge slabs of rock that cover the surface of the earth QUESTION: HOW ARE CREATING MODELS IN SCIENCE USEFUL?

EARTH’S PLATES

INFO ABOUT PLATES Continents and ocean basins are the top parts of plates. Any plate can have part or all of an ocean basin and/or part or all of a continent. The plates are what are moving and carrying the continents and ocean basins with them. Continents and ocean basins do not move on their own without the plate moving. You are learning about the outer layer of the earth.

CREATING A MODEL What do we know so far about plates that would be important to include when constructing a model to explain what they are? You are going to build models with everyday objects and compare the advantages and disadvantages of each model for how well they represent plates (not continents). You will make three models. After this, we will take a gallery walk to determine which model is best.

JUDGING MODELS GroupMODEL 1MODEL 2MODEL When looking at the models, do the following: what makes the model a good one? What limitation does it have?

QUESTIONS ABOUT THE MODELS Which do you think is the most accurate model? Why? What characteristics of that model are most accurate? What are the limitations of that model? Does anyone believe that a different model is most accurate? Why? Why is the model with the crackers as plates a good model for the earth’s plates? (The crackers are rigid and likely have different sizes and shapes if they are broken into pieces.) Can you come up with another way to model Earth’s plates? Is there any way to improve any of these models to make them more accurate representations of Earth’s plates? How?

SCIENTIFIC PRINCIPLES Earth’s surface is made of plates. These plates are not all the same size or shape and they cover the entire surface of the earth. The plates on the earth’s surface move

LESSON 4 What Makes the Plates Move

There are different elevations (topography) of the oceans and continents, including where mountains are located in both areas and where trenches can be found in the oceans (deep canyons).

The mid-ocean ridge can be seen in the middle of the Atlantic Ocean and is the place where new rock is being formed. This rock is younger compared to the rock farther from the ridge.

Scientists in the past found different types of evidence to suggest that the continents used to be clustered together, often far from their current positions on Earth.

The distributions of some of the plant and animal fossils that lead scientists to this conclusion.

There is a worldwide pattern of earthquakes and volcanoes

EARTH’S PLATES

What do you notice about the placement of the red stars?

BRAINSTORM How does convection occur in air, as happens in weather phenomena? (Convection in air is the result of differing temperatures [over land vs. over water]. For example, hot air over the land rises and cool air moves in from the ocean to take the hot air’s place. This leads to a convection cycle in which air is moving as a result of temperature differences.)

DEMO #1 You should observe that the red and blue water begins to pour out of the hole in the foil immediately. The red water moves straight up to the surface of the water and spreads out. The blue water moves straight down to the bottom of the tank and spreads more slowly. Even after 10 minutes, the colored bands of water can be seen separately—they have not mixed due to the differences in water temperatures

DEMO #2 You should observe that the red food coloring in the center rises upward toward the surface because the water is being heated by the heated beaker below. As the water gets heated and moves upward, it moves outward toward the edges of the tank/tub. It is the horizontal movement at the upper part of the earth’s mantle that is responsible for the movement of plates We will place several small pieces of cardboard next to each other on the surface of the water. Observe what happens to the cardboard.

DEMO PART 3 You should note that the blue food coloring will begin to move toward the center to take the place of the rising warm water. This blue water will then become warmer (since it is now positioned over the heat source) and will rise as well. You should be able to observe two convection cells in this model.

THINGS YOU NEED TO KNOW The heat source is the earth’s core, and the heat transferred from the core is constant. There are numerous convection cells/cycles around Earth, and they move in different directions. While you saw convection occurring on a very short (quick) timescale, in the real world, plates move VERY slowly—about several centimeters each year.

MAKING SENSE What did you observe in the first demonstration with the red and blue water from the beakers? (The red/hot water moved up to the top of the tank and spread out quickly. The blue/cold water moved straight down to the bottom of the tank and spread out more slowly.) How can you explain what happened with the hot and cold water? When you observed the demonstration with the cardboard floating on the water, why do you think the cardboard pieces moved the way they did? (the water was moving/convecting and carrying the cardboard with it when the hot material began spreading out at the surface of the water in the tank.)

REVIEW OF ACTIVITY What do the pieces of cardboard represent? (The cardboard represent plates on Earth.) What does the water represent? (The water represents the convecting and fluid mantle of the earth [directly underneath the plates].) What does the beaker of hot water represent? (The beaker of hot water represents the hot core of the earth [heat source].) What is the purpose of the food coloring? (The food coloring acts as a marker that allows students to observe the convection/movement of water due to temperature differences.)

IMPORTANT INFORMATION The mantle is a thick layer immediately beneath the surface. This layer is actually much more solid than the water, and its consistency is more similar to Silly Putty ® Imagine a tank full of Silly Putty ® that convects much more slowly. Thus there are some serious limitations of this model What are some limitations of this model?” The reason hot material rises is because it is less dense than cool material. All matter is made up of particles called atoms. When the material heats up, the particles in a certain region move farther apart, resulting in a region in which the material is less dense

NOTES TO TAKE The mantle of the earth (the rock beneath Earth’s plates) can get so hot due to heating from below that it acts like a fluid as hot material rises and cool material sinks. This sets up a convection cycle. This occurs because when it is heated from below, regions of the fluid can become warmer than other surrounding regions, which will rise above the colder regions. It is the upper horizontal part of the convection cycle that is most important to plate movement because this is what drags the plates (or cardboard in their model) along at the surface

LESSON 4.2 Silly Putty Rocks

BACKGROUND KNOWLEDGE What do you know about metamorphic rocks? (shoulder partners) Then answer on IQWST 4.2 Is the Silly Putty ® a solid or a liquid?

DESIGNING THE EXPERIMENT Answer the following question: How Does Temperature Affect the Behavior of Putty? Create a hypothesis with the following structure: If ________________________________________, then_______________________________________________________. What are the conditions of the experiment? What variables will you use? How will you measure?

NOTES TO TAKE Rocks can become deformed in the earth’s mantle. Rocks are heated (they do not need to melt just get very hot) so that they can flow and move. Hot rocks become less dense and rise to the surface Earth’s plates ride along horizontally on the surface and move when the hot material in the solid mantle moves. The rocks are very hot, but they are not melted (liquid)— instead they remain as solids but can slowly flow over time