Most of the students for whom I am preparing this curriculum unit have immigrated from Puerto Rico, Mexico, and the Dominican Republic. As such, they have had some experience with tropical storms, have seen strong rains, water overflow, erosion, and earthquakes. They wonder why these things occur. I am delighted to be able to teach them about these natural phenomena and global changes. My interest in writing this curriculum unit is to bring the students inside of something very important to humans, animals, plants, etc. I want to engage them in natural occurrences on our planet by immersing them in a study of natural phenomena.
Presenting such complex phenomena to my particular students will prove challenging. These middle school students have been labeled as Educational Mentally Retarded (EMR) or Socially Maladjusted (SMA). They have no independent reading and writing skills, and their reading levels range from pre- to grades 1-8. Most have a very short attention span, hyperactivity, a low frustration tolerance, and very low or no interest in academics. Because of their low comprehension skills and short attention spans, I decided to cover a wide range of topics, to spend only a short time on each of the natural phenomena, and to use a wide variety of visual materials. Instruction will proceed in a simple, clear, visual, and concrete manner. Activities will allow the students to recount the vivid experiences that they faced while they lived in another place.
This curriculum unit will cover four weeks. In the first week, we will discuss the sun, the earth, earthquakes, and volcanoes. The second week concerns mountain valleys, deforestation, and erosion. In the third and fourth weeks, the subjects are rivers, oceans, the coastline, water floods, and storms.
First Week: The Sun, the Earth, Earthquakes, and Volcanoes
-films about the sun, the earth, earthquakes, and volcanoes
-bulb light with electric cord
-illustrated posters of the solar system and other related pictures
Words to study:
Whenever I start teaching about the solar system, my students ask me questions like these: If the earth is moving, why don’t we move, too? Are the sun and planets just hanging there? Can they fall and splash us on Earth? Why do the stars appear so tiny in the sky? How come the water on Earth does not spill off the planet? and so on. In order for me to answer questions such as these presented by my students, who are slow learners, I need to use simply written and amply illustrated, colorful books as well as other visual materials, for these aids help facilitate comprehension. From young readers’ books of science I have found easy explanations that help me to answer their questions.
Showing a chart of the solar system, the teacher will say: “Think of the sun hanging in space like a giant glowing ball. Think of the bright moon and stars all floating through space. And we here on Earth are floating along with them.”
(1) The teacher here will use the globe, a light bulb, and other round objects to demonstrate the spinning position of the planets. The teacher also could take the students to the science lab so that they may see and touch the equipment.
Having given the students a more clear idea about how the planets rotate in space, the teacher will introduce the topic “Earth”. Again in a simple and concrete manner, holding a globe, the teacher will say, “We know that the planet earth is round like a ball; but it is not perfectly round. The crust, the outer part of the Earth, is made of solid rock. The continents and the floor of the ocean are on the surface of this crust. Below them are many miles of solid rock. Beyond the crust, you would come to the mantle; this layer of earth is made of very hot rock. Next you would see the outer core. Scientists believe that the core is made of melted metals such as iron and nickel. At the very end of earth, you would see the inner core. Here the scientists think that the iron and nickel are solid.”
Here the teacher will present a picture of the earth’s surface, both beneath and on top of it. Ask the students to draw the picture below of the earth’s surface in cross section, to label the parts, and to color it. (Figure A).
Question: Why don’t we fall off the earth? What holds us down?
We don’t fall because we are pulled back by “gravity”. Gravity is a very strong force that keeps us from falling, or in this case, from floating in space. Think of how a magnet holds onto things made of iron. Gravity pulls us in the same way that the magnet pulls the iron. Earth’s gravity pulls everything that is on or near the earth’s surface to that surface. When things are far away from the earth’s surface, gravity has less force. That is why things appear to float in space.
Note: Here the teacher could show a film about spaceships. Also, the teacher can do some experiments with pieces of paper and heavier objects, also with magnets.
How magnets on earth are produced:
The teacher explains that the rotating outer core of the earth produces a magnetic field for the earth. Students will draw a picture of the earth in cross section illustrating gravitational force (Figure B).
Question: If the earth moves, why don’t we notice the motion?
The teacher will start by saying: Imagine you are outdoors in the morning. It is still dark. Soon you see the sun begin to rise. Then we have daytime. Later that afternoon, you are outdoors when the sun begins to set. Slowly the sky grows dark; then it is nighttime again. Here the teacher asks: Is it really true that the sun comes and goes, rises and sets? To demonstrate the answer to this question, the teacher holds a globe and a bulb light, which is plugged into an outlet. The teacher moves the globe around on its own axis and says: the sun does not move; it is earth’s movement that gives us daytime and nighttime. The earth rotates or spins all the time. As the earth rotates, only half of it faces the sun. When this happens, it is daytime on the light side. The other part of the earth that is unlighted is nighttime. This is the reason that nights are cooler, because at night we do not have the heat from the sun.
The teacher, still holding the globe, explains that the earth moves in another way as well. While it rotates, it also moves around the sun. Earth takes 365 days to make a complete trip around the sun. We call this a year. In the time between January 1 and December 31, the earth travels once around the sun. Here the teacher will present a film about the earth’s rotation if one is available.
-Why do we have night and day?
-How many hours does it take the earth to rotate or spin completely?
-How many hours do we have during a day?
-How long does it take the earth to complete its trip around the sun?
Throughout history, human beings have dealt with death and destruction caused by natural phenomena. Each year, thousands of earthquakes occur. Of these, about 6000 are strong enough to be felt by humans, and 800 are strong enough to cause damage to buildings. At least twenty are big enough to destroy a major city.
Using a map, the teacher will point to the following places. In Mexico City 7200 people were killed in a 1985 earthquake. In San Salvador, more than 400 people lost their lives. The worst earthquake in the United States occurred in 1906 in San Francisco, when more than 300 people died.
The teacher will say: Picture yourself shopping in a supermarket. Suddenly the building begins to sway. Apples and oranges roll out of their bins, cans and jars tumble from the shelves. You ask: What’s going on? It is an earthquake.
Whenever possible, the teacher calls on the class to share their experiences with the natural phenomena under discussion. One way to draw the students into such discussion is to talk about one’s own experiences, as with the following:
I was seven years old, living in the countryside in the Dominican Republic. It was about 1:00 one afternoon. I was in the backyard with a woman who worked in my house looking for some vegetables and herbs when I heard a strange sound and felt something wrong. The ground was moving, and the cows were moving. The woman took my arm and ran inside the kitchen. I remember seeing big pans moving on top of the oven and finally falling, pouring all the food around. Later, in the grocery store that my father had, I saw all the cans and bottles falling and breaking into pieces on the floor. My parents and other adults were around me talking nervously and praying; they told me this was an earthquake. The tremors continued for three days off and on. I remember seeing many things that you do not see in a city during an earthquake because we did not have tall buildings and concrete houses as you do in the city. But I saw the animals, cows, horses, dogs, etc. falling on their knees. I saw big trees falling apart, the big river in front of my house changing its course, the ground opening and animals disappearing into holes in the ground. We leaned in the space of three or four days that anytime that we heard a very strange and deep sound, the earth was going to move again.
The teacher may show a film about earthquakes. The teacher says to the students: “I know that many of you or your relatives have seen a storm; but have you seen an earthquake? How old were you? Can you tell what you remember?” The teacher will allow the students to talk freely.
What causes an earthquake? The earth’s crust is made of rocks. Every day some of these rocks shift or break below the earth’s surface. This involvement causes earthquakes. Most earthquakes are too weak for us to feel. Strong earthquakes can destroy buildings, bridges, and highways. We can’t tell exactly where or when an earthquake will happen, but scientists have a good idea of where they are likely to happen. They use very sensitive machines to keep track of every earthquake. These machines are called seismographs. A seismograph can record even very small movements within the earth’s crust. Slipping and breaking rocks in the earth’s crust cause earthquakes. But what causes the rock to slip or break? Scientists say that because of motions of the earth’s mantle, the earth’s outer layers cracked into gigantic pieces called plates. They say that continents and oceans sit on these plates. These huge plates are always moving. When one plate touches another, the two plates scrape past or press against each other for a long period of time. Eventually, pressure builds up and the pressure causes the rock to suddenly slip or break, and this causes earthquakes.
How can humans avoid the damage that earthquakes cause? To avoid terrible destruction from future earthquakes, people have been asked to build their houses with earthquake resistant materials and according to designs drawn up by engineers who have studied how earthquakes operate.
In what ways do humans respond to disasters caused by earthquakes? Some of the local, national and international agencies that respond to disasters include UNICEF (United Nations International Children’s Emergency Fund), the Red Cross, and local public and private agencies. These people arrive on site to distribute food and build shelters, to treat injured victims, or to set up water purification to avoid epidemics. Sometimes other nations respond to an emergency as well.
Words to study:
The teacher will start by saying, “Imagine that you are sleeping. Suddenly you are awakened by a loud roar. You rush to a window and look out. Huge flames and great clouds of smoke and ash are rising into the air. Something hot and thick is oozing out over the ground. You are watching the eruption of a volcano.”
What causes volcanoes? We learned before that underneath the earth’s surface there are melted rocks. These rocks melt because of the heat produced by radioactivity in the Earth. The melted rock is called magma. Magma also contains gases. When the magma erupts at the surface, it forms lava flows. The hot lava spills out and flows over the land. Volcanoes also erupt explosively, spewing ash over the countryside. These explosive volcanoes are very dangerous. Winds may carry the ash far away before it falls to the ground. Eventually the lava cools and hardens into solid rock. Once a volcano starts, it may go on erupting for a long time. Or it may stop erupting and then erupt again many years later. When volcanoes erupt again and again, they build up layers of lava over long periods of time, and the layers of hardened lava become mountains. The lava that comes out of the volcano is extremely hot, about twelve times hotter than boiling water.
Volcanoes have different shapes. The shape depends on how thick the lava is and how strongly it is forced out of the vent. If there is a lot of gas inside, there will be a huge explosion and melted rock, ash and dust will pile up in a cinder cone shape. Lava that is thin and runny spreads out to make a low dome-shaped volcano.
Volcanoes can be formed and explode under the ocean, too. If they are big enough and erupt a lot of ashes and lava, they can form an island, as happened in Hawaii. The explosion can make a very strong noise. Once there was a volcano under the ocean in Indonesia. When it exploded, the noise was heard as far away as Australia. When volcanoes explode in the ocean, they can kill many people, too. They can destroy ships and kill all the fishes and other animals around.
Do you know that after many years of the eruption, all the ashes and lava that spread on the ground become a rich, fertile soil that can produce plants and vegetables? With this new plant life, new varieties of birds, insects, and other animals can now live in this area. Central Colombia contains an area with soil made rich by volcanic ash. Here high mountains tower above fertile valleys below. Over the centuries the soil on the mountain slopes has become rich in volcanic ash and is ideal for growing coffee and rice. The people who live here have become used to living in the area of disaster.
One of the most famous volcanic eruptions of all time was at Mount Vesuvius in Italy in 79 AD. For several days the mountain spewed forth lava and ash. The eruption wiped out the nearby city of Pompeii, covering it with 200 feet of ash and killing more than 20,000 people.
Here the teacher will present a film about volcanoes.
Questions: After seeing the movie, can you explain what a volcano is? How does a volcano form? Why does a volcano explode? Could a volcano explode in any area? What is the condition in the ground for a volcano to be formed? When the eruption occurs, what substance comes out of the volcano? Is it hot or cold? How hot is it? The teacher asks the students to draw different volcanoes depicting the different stages of eruption and formation.