Topic Speaking level 2 - Lesson 20 – What Is Our World Made Of?

<p>Topic: What Is Our World Made Of?</p><p>1. The Earth:</p><p>- The Earth is the planet on which we live; it’s also referred to as the world or the globe. As one of the planets, the Earth is a sphere in shape.</p><p>- Our home and the home of billions of different life forms. Scientists have estimated that our little planet is now over 4.5 billion years old.</p><p>- As of January 2023, the world population is about 8 billion people</p><p>2. What Is Our World Made Of?</p><p>The Earth is formed from Four main layers:</p><p>- The Crust</p><p>- The Mantle: Upper Mantle and Lower Mantle</p><p>- The Outer Core</p><p>- The Inner Core</p><p>2.1. The Crust:</p><p>- The surface we walk on.</p><p>- The crust ranges in thickness from approximately 5 - 69 km deep.</p><p>- It's the thinnest layer of the Earth.</p><p>- It makes up only 1% of the total volume of the Earth.</p><p>- The materials it's comprised from includes a variety of solid rocks and minerals.</p><p>2.2. The Mantle:</p><p>- It's around 2,897 km deep at its thickest point, making it by far the most voluminous layer of the Earth, comprising around 85% of the planet's total mass.</p><p>- The mantle is composed primarily of a semi-molten rock called magma.</p><p>- At the upper part of the mantle is a combination of solid rock, and rock that has been heated up by pressure so much it's become liquid.</p><p>- At the lower mantle, this rock is still hot enough to melt, but it remains solid due to the intense pressure it's under.</p><p>2.3. The Outer Core:</p><p>- Underneath the Mantle is the Outer Core.</p><p>- Earth's outer core is a fluid layer about 2.260 km thick</p><p>- This is a liquid layer of the Earth.</p><p>- The materials that make it are mainly iron and zinc. These liquids are heated to the point of being very volatile</p><p>2.4. The Inter Core:</p><p>- Earth's inner core is the innermost geologic layer of planet Earth.</p><p>- It is primarily a solid ball with a radius of about 1,220 km,</p><p>- The inner core is believed to be composed of an iron–nickel alloy with some other elements.</p><p>- The temperature at the inner core's surface is estimated to be approximately 5,430 °C, which is about the temperature at the surface of the Sun.</p><p>3. Questions and Answers</p><p>- Question 1: How many layers does the earth have?</p><p>- Question 2: What is the thickest layer in the Earth?</p><p>- Question 3: What is the thinnest layer in the Earth?</p><p>- Question 4: Which layer is the surface on which humans live?</p><p>BTVN:</p><p>- Con ôn tập nội dung bài học bằng cách thực hành trả lời các câu hỏi đã học</p><p>- Con quay video thực hành nói về chủ đề “What Is Our World Made Of?”.</p>