Rock,paper,scissors

The legend of rock paper scissors by Drew Daywalt

Rock Hunting I went hunting for rocks. I found a flat gray rock. I showed the rock to my dad. He said it was slate. Some houses have floors made of slate. I went hunting for rocks. I found a glassy black rock. I showed the rock to my dad. He said it was obsidian (ob-SID-ee-en). Obsidian can be used to make arrowheads. I went hunting for rocks. I found a light brown rock. I showed the rock to my dad. He said it was limestone. Some old buildings are made from limestone. I went hunting for rocks. I found a rock with gray and black spots. I showed the rock to my dad. He said it was granite (GRAN-it). Some kitchen counters are made from granite. I put my rocks on a piece of paper. I wrote their names under each one. My dad knows a lot about rocks. Now I know about them too!

Some things sink in water. Some things float in water. Will the rock sink or float? Will the paper wad sink or float? The paper wad floats on the water. The rock sinks in the water. Will the cork sink or float? Will the marble sink or float? The cork floats on the water. The marble sinks in the water. Will the golf ball sink or float? Will the coin sink or float? The golf ball sinks in the water. The coin sinks in the water. Will the watermelon sink or float? Will the apple sink or float? The apple floats on the water. The watermelon floats, too. Which of these things might sink? Which of these things might float? Look at the pictures. Which things sink in the water? Which ones float on the water? Did you guess right?

Lesson 1: Continental Drift Theory and the Evidences that support the Theory Continental drift describes one of the earliest ways geologists thought continents moved over time. Today, the theory of continental drift has been replaced by the science of plate tectonics. The theory of continental drift is most associated with the scientist Alfred Wegener. In the early 20th century, Wegener published a paper explaining his theory that the continental landmasses were “drifting” across the Earth, sometimes plowing through oceans and into each other. He called this movement continental drift. Pangaea Wegener was convinced that all of Earth’s continents were once part of an enormous, single landmass called Pangaea. Wegener, trained as an astronomer, used biology, botany, and geology describe Pangaea and continental drift. For example, fossils of the ancient reptile mesosaurus are only found in southern Africa and South America. Mesosaurus, a freshwater reptile only one meter (3.3 feet) long, could not have swum the Atlantic Ocean. The presence of mesosaurus suggests a single habitat with many lakes and rivers. Wegener also studied plant fossils from the frigid Arctic Archipelago of Svalbard, Norway. These plants were not the hardy specimens adapted to survive in the Arctic climate. These fossils were of tropical plants, which are adapted to a much warmer, more humid environment. The presence of these fossils suggests Svalbard once had a tropical climate. Finally, Wegener studied the stratigraphy of different rocks and mountain ranges. The east coast of South America and the west coast of Africa seem to fit together like pieces of a jigsaw puzzle, and Wegener discovered their rock layers “fit” just as clearly. South America and Africa were not the only continents with similar geology. Wegener discovered that the Appalachian Mountains of the eastern United States, for instance, were geologically related to the Caledonian Mountains of Scotland. Pangaea existed about 240 million years ago. By about 200 million years ago, this supercontinent began breaking up. Over millions of years, Pangaea separated into pieces that moved away from one another. These pieces slowly assumed their positions as the continent we recognize today. Today, scientists think that several supercontinents like Pangaea have formed and broken up over the course of the Earth’s lifespan. These include Pannotia, which formed about 600 million years ago, and Rodinia, which existed more than a billion years ago. Tectonic Activity Scientists did not accept Wegener’s theory of continental drift. One of the elements lacking in the theory was the mechanism for how it works—why did the continents drift and what patterns did they follow? Wegener suggested that perhaps the rotation of the Earth caused the continents to shift towards and apart from each other. (It doesn't.) Today, we know that the continents rest on massive slabs of rock called tectonic plates. The plates are always moving and interacting in a process called plate tectonics. The continents are still moving today. Some of the most dynamic sites of tectonic activity are seafloor spreading zones and giant rift valleys. In the process of seafloor spreading, molten rock rises from within the Earth and adds new seafloor (oceanic crust) to the edges of the old. Seafloor spreading is most dynamic along giant underwater mountain ranges known as mid-ocean ridges. As the seafloor grows wider, the continents on opposite sides of the ridge move away from each other. The North American and Eurasian tectonic plates, for example, are separated by the Mid-Atlantic Ridge. The two continents are moving away from each other at the rate of about 2.5 centimeters (1 inch) per year. Rift valleys are sites where a continental landmass is ripping itself apart. Africa, for example, will eventually split along the Great Rift Valley system. What is now a single continent will emerge as two—one on the African plate and the other on the smaller Somali plate. The new Somali continent will be mostly oceanic, with the Horn of Africa and Madagascar its largest landmasses. The processes of seafloor spreading, rift valley formation, and subduction (where heavier tectonic plates sink beneath lighter ones) were not well-established until the 1960s. These processes were the main geologic forces behind what Wegener recognized as continental drift.

What is an earthquake? Would you be surprised to learn that several million earthquakes happen every year? Seriously. Most are so small in magnitude or size that we cannot even feel them. In fact, only 20 earthquakes are efficiently reported each year in the United States Geological Survey. Wow! That is a huge difference! The Earth has four major layers. Inner core, outer core, mantle, and crust. Think of the crust and top of the mantle like the skin of the earth. This skin is made up of different pieces of rock called tectonic plates. There are about 15 major slabs that join together, kind of like a puzzle. The edges around the tectonic plates are called plate boundaries. These massive pieces of rock slide back and forth under the Earth's surface, bumping up against each other and creating a lot of tension. This tension and movement create faults, which are basically huge cracks in the rock. When the faults get stuck, they build up pressure. And when they get unstuck, you guessed it, an earthquake. So basically, an earthquake is caused by the shifting and sliding of tectonic plates on the Earth's upper mantle and crust. There are three ways that tectonic plates shift or slide. They are subduction, lateral sliding, and spreading. Subduction happens when plates crash into each other. This can cause one plate to slide under another and be destroyed. Or the edges of the plate may rise up and form mountains. Lateral sliding means that the plates slide alongside each other, which can create lots of friction. And like you might have guessed, spreading happens when plates move apart from each other. When they do, melted rock between the plates rises and cools, forming new crust. Here's an interesting fact. Nearly 90% of all earthquakes begin in the Pacific Ocean, in an area called the Ring of Fire. It's called the Ring of Fire because along with earthquakes, it's filled with many active volcanoes. More than 450! Earthquakes can be powerful enough to change the surface of the earth and can do a lot of damage. And sometimes earthquakes can even cause other natural disasters, like avalanches, landslides, and tsunamis. Pretty wild, right? The epicenter is the location of an earthquake on the Earth's surface. The closer you are to the epicenter, the more of the earthquake you will feel. Earthquakes lose intensity as they travel away from the epicenter. Scientists measure the intensity of an earthquake using a special device called a seismograph. Seismometers detect and measure the vibrations given off by an earthquake. Magnitude is the number given to record the size of an earthquake. For example, a magnitude 5.5 is considered moderate. Above 8.0 is considered a major earthquake and we see one every year or two. Earthquakes measured at 2.5 or less are usually not felt, but can be recorded. And believe it or not, there are millions that happen each year. You can make a model of a seismograph at home, and we are going to show you how. It's activity time! You can print off directions for this one on our website at learnbright.org. You'll need a cardboard box, string, a plastic cup, a marker, small heavy objects, a long strip of paper, and a friend because this is an activity for at least two people. Now comes the fun part. One friend shakes the box, alternating between hard and soft and slow and fast, while the other friend is pulling the strip of paper through the bottom. Watch the marker as it records the movement. This is exactly what a seismograph does during an earthquake. So, in a way, we have not only created our own seismograph, but our own earthquake as well. Now, we can analyze the data just like scientists. Can you tell how hard the box was shaking based on the line? Can you tell when it was barely shaking at all? You are on your way to becoming a seismologist. A seismologist is a person that studies earthquakes. It's pretty cool to watch the process, but it's even more exciting to do it yourself. You can head on over to our website to get detailed instructions for this activity. Just download the lesson plan and as always have fun! Hope you had fun learning with us! Visit us at learnbright.org for thousands of Hope you had fun learning with us! Visit us at learnbright.org for thousands of free resources and turnkey solutions for teachers and homeschoolers.

Bums in the Attic I want a house on a hill like the ones with the gardens where Papa works. We go on Sundays, Papa's day off. I used to go. I don't anymore. You don't like to go out with us, Papa says. Getting too old? Getting too stuck-up, says Nenny. I don't tell them I am ashamed -all of us staring out the window like the hungry. I am tired of looking at what we can't have. When we win the lottery . . . Mama begins, and then I stop listening. People who live on hills sleep so close to the stars they forget those of us who live too much on earth. They don't look down at all except to be content to live on hills. They 86 Sandra Cisneros have nothing to do with last week's garbage or fear of rats. Night comes. Nothing wakes them but the wind. One day I'll own my own house, but I won't forget who I am or where I came from. Passing bums will ask, Can I come in? I'll offer them the attic, ask them to stay, because I know how it is to be without a house. Some days after dinner, guests and I will sit in front of a fire. Floorboards will squeak upstairs. The attic grum- ble. Rats? they'll ask. Bums, I'll say, and I'll be happy. Minerva is only a little bit older than me but already she has two kids and a husband who left. Her mother raised her kids alone and it looks like her daughters will go that way too. Minerva cries because her luck is unlucky. Every night and every day. And prays. But when the kids are asleep after she's fed them their pancake dinner, she writes poems on little pieces of paper that she folds over and over and holds in her hands a long time, little pieces of paper that smell like a dime. She lets me read her poems. I let her read mine. She is always sad like a house on fire-always something wrong. 84 Sandra Cisneros She has many troubles, but the big one is her husband who left and keeps leaving. One day she is through and lets him know enough is enough. Out the door he goes. Clothes, records, shoes. Out the window and the door locked. But that night he comes back and sends a big rock through the window. Then he is sorry and she opens the door again. Same story. Next week she comes over black and blue and asks what can she do? Minerva. I don't know which way she'll go. There is nothing I can do.

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