(1) Cut the tissue paper into pieces of paper with specifications as shown in the figure. Stick one side of the first piece of paper and one side of the second piece of paper together, and then stick the third and fourth pieces in turn until a ball with a diameter of about 60 cm is formed.
(2) Cut a circular piece of tissue paper and stick the circular air holes on it. When it is dry, blow up the balloon, find a thin and narrow bamboo strip, bend it into a bamboo ring with the same size as the hole below, cross two thin iron wires perpendicular to each other in the bamboo ring, tie them on the bamboo ring, and then stick the bamboo ring on the paper edge of the hole below, so that the pasted balloon will not leak.
(3) Light the alcohol cotton ball and tie it in the center of the wire. After the air inside the balloon is heated, the balloon will fly from the ground to the sky.
(4) This is because the air inside the balloon is heated and expanded, and part of it runs outward, so that the buoyancy of the air received by the balloon is greater than the weight of the balloon (including the hot air inside the balloon), so that the balloon will rise.
How to write a good exposition
A: Explanatory writing is a style with explanation as the main expression. The general elements of expository writing are characteristics, composition, principles and purposes. Explanatory text should pay attention to the order and language of explanation and use necessary explanation methods. You should also pay attention to these when writing expository articles. First of all, you should be familiar with the object of interpretation, know what characteristics you want to tell readers, and how to make readers understand the characteristics of the object of interpretation. Then, when explaining complex objects, it is very helpful to use the explanation method and choose the appropriate explanation method. In addition, the language of explanatory text should be concise, smooth and clear.
Explanatory text is a text that introduces and explains things and things with explanation as the main expression. Explanatory writing generally has three characteristics: first, content science. The content of the explanatory text must be true and accurate, based on conclusive materials, truthfully reflect the characteristics, essence and laws of objective things, and be strictly scientific. Second, the order of the structure. Things and events are sometimes complicated. In order to make readers have a clear understanding, there must be a certain order and order when explaining their characteristics. The common order of interpretation is chronological order (procedural order is also a kind of chronological order), spatial order and logical order. This order of interpretation is often reflected in the structural level of the article, so it is consistent to clarify the structural level and grasp the order of interpretation when reading the explanatory text. Third, the accuracy of language. Explanatory text is very practical, and the result will be "a thousand miles away" if the language is "right", so the language of explanatory text is required to be accurate and give readers a scientific understanding. Today, with the rapid development of science and technology, the application of expository writing is more and more extensive. Textbooks, popular science books, knowledge sketches, comments and explanations of various disciplines are explanatory texts. It can be said that expository writing is closely related to our daily study, life and work.
How to read the explanatory text?
First, grasp the description object and characteristics. When reading the explanatory text, we should first accurately grasp the explanatory object, so as to distinguish the explanatory text from the explanatory text and further understand the explanatory content. Then we should focus on the characteristics of the object. This is the key to analyzing an expository article. Only by accurately grasping the characteristics of the object of interpretation can we deeply understand the object of interpretation, and take this as a breakthrough to clarify the structural level and central content of the article. ask
To accurately grasp the characteristics of the object of interpretation, we must carefully read and understand the text content, especially pay attention to carefully try to figure out the key words (central sentences, turning sentences, sentences that reflect the author's thoughts and sentences that appear repeatedly in the article).
Second, clarify the structure and analyze the order. The structure of explanatory text is not complicated. The common structural forms are "general (generalization)-secondary (concreteness)", "general (generalization)-secondary (concreteness)-general (generalization)," secondary (concreteness)-general (generalization) ",juxtaposition and progression. Clarifying the structure can help us understand the author's ideas and the main points of the content more clearly. The order of interpretation is varied. What kind of interpretation order is adopted depends on the characteristics of the object of interpretation and the purpose of interpretation. There are three commonly used interpretation orders: chronological order, spatial order and logical order. Sometimes, an article can cross-use several interpretation orders, in addition to the chronological order from ancient times to the present, there is also a logical order from generalization to concreteness, from whole to part. All kinds of sequences have certain symbols in language. Mastering the language with certain symbolic function when reading can analyze and explain the order more smoothly. In a word, the structure and order of expository texts are inseparable and complementary, and the analysis can be carried out at the same time.
Third, analyze and explain the method. In order to explain the characteristics of things clearly, appropriate interpretation methods must be adopted. Common explanation methods include examples, figures, analogy, comparison, classification, definition, explanation, charts and so on. Reading the explanatory text and understanding the explanatory method used depends on what kind of explanatory method is used, what object is explained, what role it plays, and what language form is used to express the explanatory method.
Come on, this analysis is thorough and solid.
Fourth, experience the language characteristics of expository writing. Accuracy and conciseness are the main characteristics of expository writing. Of course, the language style of expository writing is also varied, each with its own characteristics, some of which are good at simplicity and some are good at liveliness. Based on this, it can be summarized into two ways: simple explanation and vivid explanation. Generally speaking, an expository text that focuses on explaining things focuses on grasping the characteristics of things and explaining them in concise language.
Scientific sketches, which are interesting and literary, need vivid explanations.
In the local senior high school entrance examination, the examination points of explanatory reading ability mainly include:
1. Be able to understand the object of explanation, grasp its characteristics and have an overall perception of the full text;
2. Divide the article structure and paragraph level, clearly explain the order, and master the idea of article layout;
3. Analyze the method and function of the article;
4. Find out the key words (head words and key sentences) and understand their functions in the text (from ideographic and structural aspects);
5. Understand the characteristics of language expression and accurately evaluate the modification and restriction of words.
Grasp the object and its characteristics.
Overview of oral knowledge
To read an explanatory article, we must first understand the explanatory object, grasp the explanatory category, and then grasp the characteristics of the explanatory object. The syllabus stipulates that junior high school students can "perceive the general content of the text as a whole" and "grasp the center of a paragraph and find out the key sentences" Speaking of expository reading, specifically, the training points of knowledge and ability are:
1. Perceive the content of the article as a whole, grasp the object of explanation, and distinguish between things and things;
2. Analyze the content of the article and grasp the characteristics of the explanatory object.
Oral examination of direction
First, how to grasp the object of explanation and distinguish between things and things? The object of explanation, that is, the topic explained in the article, is mainly divided into two aspects: first, concrete things, including their state, nature, function and characteristics; Second, abstract things, including the essence of things, the internal relations between things or things.
Second, how to analyze the content of the article and grasp the characteristics of the explanatory object?
Introduce the shape, nature and composition of things, and explain the causes, functions and relationships of things. We must grasp the characteristics of things. The so-called "feature" is a sign that one thing is different from other things. To understand the characteristics of things, we should not stay on the surface, but understand the inner essence of things. So, how to grasp the characteristics of things? You can also start from two aspects:
First, focus on the title. Some titles point out the characteristics of the article while pointing out the object of interpretation, while others point out the characteristics of the object of interpretation. Some titles take the form of rhetorical questions to guide readers to grasp the characteristics of the explained object.
Secondly, starting with the analysis of materials, that is, analyzing the characteristics of things introduced by the author paragraph by paragraph, and then summarizing them. The author has clearly pointed out the essential characteristics of some things in the article, so we should find out these key sentences when reading.
Second, clarify the structure of the article and analyze the order of interpretation.
Overview of oral knowledge
When reading an explanatory article, pay attention to the structure of the article. The so-called "structure" refers to the organization and arrangement of the content of the article, mainly referring to the beginning and end, levels and paragraphs, transition and quotation. The structure of explanatory text is closely related to the order of explanation, which is a necessary condition for the orderly content of explanation. Therefore, while clarifying the structure of the article, we should also analyze the order of interpretation. According to the Outline, junior high school students can "see the connection between the parts of the text and roughly understand the idea and central meaning of the text". The implementation of expository reading, specifically, the key points of knowledge and ability training are:
1. Be able to sort out the structure of the article and divide paragraphs and levels;
2. Be able to analyze the order of instructions and find out the key words that represent the order.
Oral examination of direction
First, how to sort out the structure of the article and divide the paragraphs and levels?
The structure of the explanatory text (with emphasis on paragraphs and levels) is relatively clear. Usually divided into three types.
Part: the description object is introduced at the beginning, and the object is described in detail in the middle; Conclusion: Yes.
Elephant. Common structural forms are:
1. Total score formula. When explaining things or things, there is a total score relationship between paragraphs (levels), which is manifested as from total to points, from points to points, from points to points and then to points. For example, the article "Suzhou Garden" adopts the structure of "total score" and arranges the explanation order reasonably. The first two paragraphs have been talking about the artistic value of Suzhou gardens and their similarities and differences. The third to ninth paragraphs discuss the specific characteristics of Suzhou gardens, among which the third to sixth paragraphs are always closely related to the beautiful features of Suzhou gardens, respectively corresponding to the four "stresses" in the second paragraph, and the seventh to ninth paragraphs are closely related to the characteristics of Suzhou gardens in detail. This article is clear in context and rigorous in structure, which fully embodies the characteristics of Suzhou gardens.
2. bear. According to the development process of things, or according to the relationship between time, cause and effect, conditions, etc. , each layer to undertake each other.
3. progress. On the basis of the former, it further shows that the relationship between layers is from shallow to deep.
In addition to the above three structural modes, there are parallel types (the relationship between layers is parallel and parallel) and so on. It will be easy to understand and master the common structural forms, structural analysis and paragraph hierarchy division of explanatory texts.
Second, how to clarify the order of instructions?
To clarify the characteristics of things, there must be a reasonable order. Explanatory texts usually adopt three interpretation orders: spatial order, chronological order and logical order. So, how to analyze and explain the order?
1. Identify the description object and analyze the description order. The characteristics of description objects determine the choice of description order. Some things have complicated internal structures, which are usually arranged according to spatial order's instructions, from front to back, from top to bottom, from outside to inside, from middle to around, or in the order of east, west, north and south. A clear understanding of the object of interpretation can help us understand the thinking of interpretation and further clarify the order of interpretation.
2. Master the language symbols and "read" the order of instructions. Explanatory paragraphs often use certain words to express hierarchy and order, connect content and organize materials. For example, a sequential multimeter is a word with time variation, a word with spatial order multimeter direction, and a logic level related word of a logical sequential multimeter. Therefore, by grasping these linguistic "symbols", we can smoothly sort out the order of interpretation.
3. Prioritize and summarize. As far as an article is concerned, sometimes not only one interpretation order is adopted, but several ways are combined to achieve a thorough interpretation effect. This requires a clear distinction between primary and secondary, analysis and comprehensive induction.
Oral examination of direction
First, how to identify the interpretation method? There are many ways to explain it. An explanatory text can be interpreted in different ways according to actual needs, sometimes alone and sometimes in combination. Therefore, we should read carefully and distinguish carefully when analyzing. Column numbers also have specific figures. We should also pay attention to the comparison of the contents of the two sentences, highlighting the influence of artificial selection on the sentences, which means that the method of comparative interpretation is also used here.
When analyzing interpretation methods, we should distinguish between types and primary and secondary ones, and make clear which one is the main one, so as to better grasp the characteristics of the explained object. The explanation method here is mainly for comparison. In addition, two vague understandings must be clarified when analyzing and explaining this method. Some students often confuse interpretation with rhetoric. In fact, the objects and expression effects of the two services are obviously different. The figures and events are expressed more vividly by using metaphorical rhetoric in narrative. Analogy is used in explanatory writing to better explain the characteristics of things. Some students saw narrative words and thought they were "examples". In fact, legends and stories are sometimes quoted to enhance the vividness of explanatory language and stimulate readers' imagination and interest. Sometimes it's just a general narrative, which is a skill of writing articles.
Second, how to understand the role of interpretation?
The first step in analyzing interpretation methods is to identify the types of interpretation methods, with emphasis on understanding their functions.
Adopting certain interpretation methods is to better explain things and their characteristics. Appropriate methods can make unfamiliar things familiar, abstract things concrete, complex processes simple and easier for readers to understand and accept. Generally speaking, enumerating figures can give people a precise and concrete impression; Metaphor can enhance the vividness and vividness of explanation; Examples can reflect the general situation and truly explain things; Definition can make readers have a clear concept of the object of interpretation; Classification can receive comprehensive and clear expression effect; Comparison can make the characteristics of things that are difficult to explain clearly easy to understand, clear and specific. To analyze the function of interpretation methods, we must comprehensively consider specific sentences and language environment and analyze them realistically.
In short, to analyze the function of interpretation methods, we should first grasp the "general direction"-the characteristics and functions of various interpretation methods, and then combine the specific language environment-concrete analysis and comprehensive induction to "fill in the blanks" reasonably, so as to explain the characteristics of things more accurately, comprehensively and clearly.
Fourthly, analyze the language features of expository writing.
Overview of oral knowledge
Reading explanatory texts, accurately grasping the explanatory objects and their characteristics, and accurately summarizing the meaning and center of paragraphs are inseparable from language analysis. The syllabus stipulates that junior high school students can "read ordinary modern texts, understand the meaning and function of words in the language environment, and have certain language perception ability", "feel the thoughts and feelings expressed in the text language", "understand the meaning and function of words in the context with the help of reference books" and "experience the deep consistency of some sentences in the text". When it comes to expository reading, specifically, the knowledge points and abilities are:
1. Can understand the accuracy of descriptive language;
2. Be able to accurately grasp the key words in the explanatory text and analyze them in the text.
Function.
Oral examination of direction
First, how to understand the accuracy of explanatory language?
Accuracy and conciseness are the main characteristics of expository writing. Try to find out the accuracy of explaining the text language, focusing on how words and sentences explain the characteristics of things, so as to understand its function and its beauty.