Eighth Grade Science Paper

1. Why are tree trunks round?

In the process of observing nature, I accidentally discovered that the shape of tree trunks is approximately round - hollow cone-shaped. Why are tree trunks conical? What are the benefits of conical trunks? In order to explore these issues, I conducted more in-depth observations and analysis.

With the help of the tutor, I checked the relevant information and learned that the stems of plants play a role in supporting the plant body and transporting water and other nutrients. The stems of trees are mainly composed of vascular bundles. The supporting role of the stem is mainly borne by xylem wood fibers. Although the stems of woody plants will become thicker year by year, within a certain time range, the number of wood fibers in the stems is constant, that is, the cross-sectional area of ??the tree stems is constant. Next, we designed experiments around a certain cross-sectional area of ??the tree trunk, assuming that the cross-section of the tree trunk grows into different shapes, to explore the reasons and advantages of the conical shape of the tree trunk.

After experiments, we found that: (1) When the cross-sectional area and length are constant, the longitudinal supporting force of a triangular prism-shaped object is the largest and the lateral bearing force is the smallest; the longitudinal supporting force of a cylindrical object is not as good as that of a triangular prism-shaped object. But the lateral bearing capacity is the greatest; (2) Among trunks of equal mass and different shapes, short cone-shaped trunks bear the greatest wind force; (3) Wind is a natural phenomenon that affects the shape of the cross-section of trees and the height of tree growth. The nearly conical trunk has a low center of gravity, and the huge root system is connected to the earth, so the center of gravity is lower and the stability is greater; (4) The trunk has a round cross-section, which can reduce damage and has stronger mechanical strength. , can withstand the attack of wind. At the same time, due to the influence of wind, the bending degree of the tree trunk is similar everywhere. No matter which direction the wind comes from, the resistance of the tree trunk is similar, and the tree trunk is not easily damaged.

The above experiments reflect the laws of nature and the inspiration given by nature: (1) A columnar object with a triangular cross-section has the greatest longitudinal support, and its shape can be used in construction, such as angle steel, etc.; (2) ) is a round object with a circular cross-section and has the greatest lateral bearing capacity. Building materials of similar shapes can be found everywhere, such as TV towers, telephone poles, etc.

In the process of my observation, experiment and analysis, I gradually explained and revealed the mystery of the conical shape of the tree trunk, increased my knowledge, and applied the learned knowledge with practice, which not only consolidated the learned knowledge Knowledge, increased interest in learning, and initially learned scientific observation and analysis methods.

2. How to write a scientific essay

The National Youth Invention and Science Symposium has been held every two years since it was held in Shanghai in 1982. It has been held for 10 years so far. (renamed the National Youth Science and Technology Innovation Conference from the 10th session in 2000), it has become a traditional project of science and technology activities in primary and secondary schools and an important part of school education. Many students’ excellent works have been published in newspapers and periodicals across the country, and some have won awards nationally and even internationally!

1. What is a scientific essay?

Some students write Scientific papers are seen as mysterious and are considered to be the business of scientific workers and are out of reach for us children. This is completely a misunderstanding. Students can not only write but also write high-quality papers.

Scientific papers written by scientists refer to the author obtaining a large amount of scientific data through experiments, observations and other means based on the formulated scientific research projects and determined scientific research topics. On this basis, he then conducts Analyze research, draw scientific conclusions, and write scientific research reports. The scientific papers written by students are shorter and shallower than those written by scientific workers.

A short science paper is actually a written summary of the results of scientific observations, experiments, or inspections made by students in scientific activities inside and outside the classroom. Its forms of expression are diverse: it can be a conclusion drawn after careful observation and in-depth thinking about something; it can be a conclusion drawn after analysis after hands-on experiments; it can also be a summary after an inspection of a certain place; You can also draw conclusions through logical reasoning...

So, are there quality standards for scientific papers? have. It must possess "three qualities".

1. Scientific. Scientificity is one of the important features that distinguish scientific essays from other types of articles, and is the life of scientific essays. It requires scientific topic selection, correct research methods, solid arguments, reasonable and logical arguments, and concise and accurate writing.

2. Creativity. The topic selection and main points of the short paper should have new discoveries and unique insights, and have certain practical significance for people's production and life. The same small paper has not participated in scientific seminars at all levels, nor has it been published at all levels. Published in newspapers. Of course, if you further research based on other people's research and come up with novel, original, well-documented and reasonable insights, it is also feasible without losing creativity.

3. Practicality. The topic selected for the paper must be discovered by the author himself during scientific exploration activities; the arguments supporting the main points must be obtained personally by the author through observation, investigation, experiment and other research methods, and have a practical basis; the paper must be written by the author himself. There should be no signs of fabrication, speculation, or substitution by adults.

The above "three properties" are the quality standards for measuring the quality of scientific papers.

For example, when writing "Sunflower", although your observations are meticulous, its posture is vividly described, and its character is analyzed perfectly, if you do not get a scientific and meaningful conclusion, it can only be regarded as a good article at best. Essays or observation journals, not scientific essays.

Writing a scientific paper is a very hard work, and it is also a very meaningful activity. Success belongs to young friends who have the courage to explore and pursue unremittingly!

2. Types of scientific essays

The most common forms of scientific essays are scientific observation essays, scientific experiment essays, scientific investigation essays and scientific explanation essays.

(1) Scientific Observation Essay

A scientific observation essay refers to a young person’s careful observation of something or a natural phenomenon, and a careful review of the materials and data obtained. Draw conclusions after analysis and comprehensive research, and make scientific explanations and descriptions.

The father of Hunan classmate Liao Hao often coughs. Through long-term and repeated observations, he discovered that the wind direction is closely related to his father's cough, and found out the "culprit" - the Hunan Rubber Factory. There was a lot of smoke coming from the big chimney, which contained sulfur dioxide. When Dad smelled it, he had an allergic reaction in his throat, which reflexively caused him to cough. His short paper "Dad's Cough" mainly uses observation as a research method to draw conclusions. It is a scientific observation paper and won the third prize at the Second National Youth Science Symposium.

It should be noted that the objects studied in scientific observation essays are objectively existing natural things or phenomena, which occur under natural light conditions without human control, so the content described in the article should be It is the object, process and the conditions and various phenomena that are observed by the author. No artificial conditions or personal biases can be attached. In addition, observation is a long-term, systematic, and repeated activity that requires the author's patience, meticulousness, and perseverance.

(2) Scientific experiment essay

Scientific experiment essay, sometimes also called "experiment report", is a teenager who creates specific conditions for the research object. After repeated experiments, the An article written by analyzing the obtained materials and data and drawing conclusions based on synthesis. It focuses on the objective narrative of the experimental process and the scientific explanation of the experimental phenomena.

Many students know that ivy can climb walls. But why can ivy climb walls? Xiong Bin, a classmate from Wuhan, discovered through observation that this was related to the "tentacles" of the ivy. Then he calculated that there were an average of 25 "tentacles" adsorbed on the wall on each meter-long ivy stem, and made a "tension of the tentacles". "Measurement and Adsorption" experiment, the purpose of the experiment is clear, the experimental steps are detailed, the data is accurate, the explanation is strong, and the conclusions drawn are true and credible, it can be regarded as an excellent scientific experiment paper.

(3) Scientific investigation paper

You want to study the pollution level of a certain water area that is closely related to people’s lives, the source of air pollution in a certain place, and understand the evolution of a certain strange rock and mountain. , animal and plant resources and distribution in a certain range, etc., you have to conduct on-site inspections. Essays written through surveys, visits, field exploration and other investigation methods as the main research methods are called scientific investigation essays. Sometimes also called "scientific investigation report" or "scientific investigation report".

In the article "Wish the Water of Shengtian Reservoir to Be Evergreen", which won the first prize at the 5th National Youth Science Symposium, the young authors conducted an on-the-spot investigation of the geographical and ecological environment and storage capacity of the reservoir. We also conducted actual measurements to the best of our ability to find out the hidden dangers in the reservoir and put forward more reasonable suggestions. In addition to stating the time, objects, content and conclusions of the comprehensive analysis, the article also draws the "Rainwater Collection Map of Shengtian Reservoir" and "Schematic Map of Strong Erosion of Zhongshan", plus some actual data, so that readers can understand the investigation. The object has a relatively general and clear understanding.

When writing a short paper on scientific investigation, you should sometimes attach relevant specimens or photos of animals, plants, rocks, soil, etc. to the end of the article to enhance your persuasiveness.

(4) Scientific Explanation Essay

Scientific Explanation Essay refers to a type of essay in which the author uses detailed and reliable information to explain and explain a certain natural phenomenon or natural thing. paper. Generally speaking, it does not directly use observation, experiment, inspection and other research methods, but mainly obtains rich second-hand materials from books, periodicals, teachers, etc., and uses its own understanding through its own comprehensive analysis and logical reasoning. language to illustrate a point.

"Why Guiyang is the Second Spring City of the Motherland" is a short paper that won the third prize at the 2nd National Youth Science Symposium. The author's research method has its own special features. First, it uses Radio and television insist on recording and sorting out the weather and temperatures in Guiyang and Kunming; second, use the ready-made scientific research results "Climate Atlas of China" to find representative temperature conditions in Chongqing and Beijing to compare with Guiyang and Kunming; The third is to check the average temperatures of Kunming and Guiyang in January, April, July and October from books, and then draw conclusions through comprehensive analysis.

Although this type of article does not have the evidence obtained from personal practice of the first three types, it is after all that the author carefully collects and organizes information and comprehensively analyzes it to put forward new viewpoints and new insights, so it is also recognized as Scientific essay.

A special reminder is that when writing a scientific explanatory paper, you must not ask a question and then rush to look up the information, and then copy and explain without analysis. This will have no new ideas and no new insights. The article can only be regarded as a general science article, and cannot be called a scientific paper, let alone cultivate your own ability to research problems.

3. Topic selection for scientific essays

The first step in writing a essay is to determine the object of research and consider what issues to study. This is topic selection. Some people say that choosing a good topic is equal to half of completing a small thesis, which shows the importance of choosing a small paper topic.

Some students said that there are so many wonderful phenomena in nature, what should we study? Some students said that I am used to seeing things in nature and have not discovered anything new. Besides, what I want to study has already been studied by others, so there is not much point in writing about it.

In fact, as long as you understand the basic principles of topic selection, master several common methods of topic selection, and be a thoughtful person in daily study, life and scientific and technological activities, you will definitely find something worth discussing. topic.

There are many ways to choose a topic for a science essay, and individuals can make timely choices according to different situations. Here are several common topic selection methods for students to refer to when choosing topics.

1. Accidental discovery method. One Sunday, Songzi’s classmate Hu Changcheng was playing by the ditch behind his house. There were many tadpoles swimming around in the ditch. Suddenly, he found a little tadpole that seemed to be at odds with the other tadpoles, swimming alone on one side. He used a small branch to pull the tadpole out of the group into the group of tadpoles. After a while, it swam alone to the side again. He felt strange, so he put him and several other groups of tadpoles in bottles and kept them at home for observation. Finally, the unsociable tadpoles became frogs, and the others grew into toads. Through long-term observation, he figured out the difference between the young of frogs and toads, and wrote an excellent little paper.

This kind of topic selection is not considered in advance, but just becomes interested in the fleeting phenomenon discovered by chance, so that we can hold on to it and trace the source.

2. Classroom extension method. In the primary school science class "Animals and the Environment", students studied the relationship between earthworms and light, temperature and moisture, and found out that earthworms like dark, supermarket, and warm environments. They also learned to use the difference method to conduct experiments to determine the cause and effect of errors. . After class, you can use the methods you have learned to study the living environment of centipedes, crickets, ants and other small animals. You can continue to study other mysteries of earthworms: For example, do earthworms have eyes? Do earthworms open their ears? Earthworms’ regeneration ability, soil loosening ability, etc.

3. Question inquiry method. Flies are really annoying little things. They are the main culprit of infectious diseases! But he is also really surprised that it is often exposed to various bacteria but why doesn't it get sick?

Sleeping can relieve fatigue and restore energy. Do the fish that wander leisurely in the water all day also sleep?

…

In daily life and study, you will definitely have some questions that you don’t understand. Can you use them as the research object of your short paper?

Mao Dengsheng, a fifth-grade student in Daoxian County, Hunan Province, was playing in the bamboo forest near the school with several classmates one day, arguing endlessly about whether the bamboo was empty or contained something.

The careful Mao Dengsheng always kept this question in mind. He checked information and did experiments after class, and used a lot of evidence to come to the conclusion: Bamboo is not empty inside, but contains air, oxygen, nitrogen, Gases such as carbon dioxide. The essay "What's in Bamboo" written based on this won the first prize in the first National Youth Science Essay Competition.

4. Teacher guidance method. If you have raised a small animal or cultivated some flowers and are studying them but don't know where to start, you can ask the teacher for advice and let the teacher choose the topic based on your actual situation and conditions.

If you join the school's science and technology group, you can tell the teacher your research ideas and ask the teacher to determine the research topic, and then you can observe and experiment around the topic.

For example, under the guidance of teachers, the students of the Biology Group of Chongqing Renmin Primary School chose some inspection and research topics and completed the "Survey on the Characteristics of Chongqing Yellow Horn Tree" and "The Water Conditions of Yuanshengtian Reservoir". Green" and many other short essays, and has won the first prize of the National Youth Essay Award many times.

5. Scientific verification method of idioms and proverbs. Most idioms are created by people in their long-term social life and practice, but some come from fables, folklore, and some are established by convention. A few of these idioms do not necessarily conform to objective reality. You can use scientific methods to analyze and verify.

The idiom "drops of water can penetrate a stone" is familiar to everyone. It means that water dripping continuously can penetrate a stone. It means that as long as you persevere, you can do something that seems difficult even if you have little strength. matter. But common sense tells us that a "water drop" is just a drop of liquid. Its power is very small and its impact speed is not too fast. How can it penetrate a hard rock? The member students began to have doubts about the scientific nature of this idiom. They verified the scientific nature of this idiom by doing simulation experiments and consulting information.

"The spring east wind brings rain to the ancestors" is a widely circulated meteorological proverb.

A classmate made detailed observations and records of the temperature, wind direction, and weather conditions for a month in March, and then used scientific statistics to figure out the applicable scope of this proverb, which provided a reference base for weather forecasting.

Is it true that "sunflowers bloom toward the sun"? But Hunan student Jiang Linbo challenged this conclusion. Through two years of experimental observations, he came to the conclusion with convincing arguments that "sunflowers do not always turn toward the sun" and "sunflowers follow the sun during the bud stage, and stop turning after blooming."

From this point of view, even for conclusions that have long been recognized, we must study them carefully and do not follow what others say. Only in this way can innovation be achieved.

Special attention should be paid to the subjective and objective conditions when selecting the topic. As the saying goes: "Know yourself and the enemy, and you can fight a hundred battles without danger." When choosing a topic, you need to figure out what your strengths and weaknesses are, whether you are interested in the research question, whether you have the ability to study it clearly, whether you have reached this level of knowledge and understanding, and whether you have the perseverance. To complete this topic and whether we have the experimental equipment, venues, etc. to study this problem.

If you complete the topic "Exploring the Mystery of a Kind of Snake", you must master the basic knowledge about snakes before doing the research, have the ability to catch snakes, be able to distinguish between venomous snakes and non-venomous snakes, and understand how to be bitten by venomous snakes. rescue methods. In addition, you must have equipment for raising snakes. Otherwise, it is better to change to a topic that is more in line with the subjective and objective conditions.

4. Material collection and analysis of the short paper

After the topic selection is determined, the material collection and analysis can be carried out. The specific content is to formulate a research plan, collect and organize data, and carry out in-depth on-the-spot investigation. Conduct observation experiments, analyze various materials, and draw conclusions through induction.

(1) Collection

1. Direct observation. It means to look carefully with your eyes. It is a method for people to investigate natural phenomena under naturally occurring conditions.

Be careful when observing and not miss any detail. Yunnan Zhuang Yueping spent 2_0_ days observing the whole process of domestic pigeon hatching in detail. He made new discoveries almost every day, not even a black spot on the little pigeon or a wrinkle on the eyelids, so he wrote the short paper " Observations on Domestic Pigeon Hatching" is authentic, credible and rich in content. At the same time, detailed records must be kept during observations, otherwise it will be impossible to obtain true first-hand information.

2. Hands-on experiments. The experimental method is to artificially intervene and control the object of study. It is more conducive to unleashing the initiative of students to reveal the hidden mysteries of nature than observation.

What is the function of an insect’s hind legs? Zhang Jun from Hubei Province caught more than ten kinds of insects, including locusts, grasshoppers, and crickets, and cut off their hind legs respectively. Through repeated experiments, observation and comparison, he discovered many special functions of insects.

3. On-site inspection. Including surveys, visits, on-site exploration and other methods. Before the inspection, the purpose of the inspection must be clearly defined and the necessary tools, instruments, medicines, daily utensils, etc. must be prepared. During the inspection, you must record the time, location, process and inspection results in detail at any time and at any time. Sometimes you also need to collect necessary specimens and samples and take photos of more important phenomena. These are very useful first-hand Material.

4. Check the information. Some materials are impossible to observe, experiment, or inspect in person due to limitations of time, space, or objective conditions. In this case, you have to consult books and periodicals or ask teachers, parents, etc. This kind of indirectly obtained material is called second-hand material. Some problems cannot be solved by your knowledge level, ability and conditions, and this problem is a problem that must be solved in your topic selection, so you have to check the information and clarify it.

(2) Analysis

After obtaining the materials, it is necessary to conduct analysis and research, select materials that can be used as arguments, and remove the rough and fine based on the arguments, remove the false and retain the true, and follow the Organize and analyze with a scientific attitude and draw your own arguments and opinions.

First of all, the authenticity of various materials should be reviewed. Some of the materials accessed are outdated views, some explanations are only suitable for a certain range, some materials are not universal, and some materials are recorded. If it is an error or is made up by oneself, such materials should not be used.

Secondly, we should pay attention to the typicality of the materials, that is, the selected materials should be able to illustrate the problem, not too many, but precise. Materials that have nothing to do with the argument or have little relationship should be discarded.

Third, classify the selected materials, study the similarities and differences between them, as well as their mutual connections, and then summarize and draw conclusions, which are arguments. The argument of the paper is generated from the analysis and research of materials. You cannot decide the argument first and then find materials suitable to prove the argument. For example, Xiong Xiaojia studied the eyesight of earthworms. She chose 4 materials (1) wooden sticks, red scarves, The phenomenon of pencils and other materials shaking in front of earthworms; (2) The reaction of earthworms to various foods; (3) The reaction of earthworms placed at the door of the "house"; (4) Please ask Grandpa to get information about whether earthworms have eyes. Through the analysis of the first three experiments, it was initially determined that earthworms have no eyes and rely on their sense of smell to find food and photoreceptor cells to find dark places. The fourth material further confirmed her inference, making the argument fully demonstrated and more convincing.

5. Writing a Scientific Essay

After you have completed the organization and analysis of the materials, you can start writing. Although there is no fixed format for writing, it should generally follow the steps of asking questions, making assumptions, researching and analyzing, and drawing conclusions. Generally speaking, a scientific paper should include the following parts.

Title

The title is the "eye" of a small paper. A good title is precise, concise and attractive. It can give readers a fresh feeling and a deep impression, and it plays a finishing touch. .

The so-called "accurate" means that the title of the essay must summarize the central content of the article so that people can understand it at a glance. It cannot go off topic or be lax about the topic, let alone use exaggerated words. The so-called "concise" means that the title should be concise, it should be comprehensive and comprehensive, and it should highlight the theme and be concise and meaningful.

Beginning

There are many ways to start, depending on the research content and your favorite writing style, but generally you should get straight to the point and ask the question you are discussing. How did you come up with the idea? study this issue.

The article "Why is Guiyang said to be the second spring city of the motherland" begins: "I live in Guiyang and often hear people say 'Kunming is the spring city and Guiyang is the second spring city'. As for why, I can't figure it out. Understand, I am determined to record the weather forecast to see if Guiyang is really the second spring city?" The desire to verify its scientific nature arises from the saying.

Some articles’ problems are generated and discovered through accidental observation. You can also describe the process in chronological order at the beginning, and then ask questions when appropriate.

Text

This is the part that analyzes and solves problems. It includes making assumptions, observations, experiments, inspection processes, discovered phenomena, judgments, reasoning and drawing conclusions on the questions raised, etc. This is the core part of the short paper.

It should be noted that: the research steps should be written in detail and appropriately, the experimental process, the origin of the data, and the phenomenon should be clearly written, and the description should be in a certain order. Data materials must be accurate and can be designed into tables and diagrams that can explain the problem. If necessary, photos taken, specimens collected, etc. can be attached to enhance persuasiveness. The conclusions obtained must have their own unique insights and be consistent with the arguments, and the arguments must be strictly logical. The text should be concise and vivid, with clear levels and clear organization.

Ending

The end of the essay should include your conclusions and suggestions for a certain issue.

The article "Earthworm Vision" ends: "Oh, I understand. Earthworms are blind to the letter. They rely on their sense of smell to find their favorite food and use photoreceptors to distinguish the intensity of light. Weak." It ends with a conclusion, which echoes the questions raised at the beginning and has a good effect.

After the first draft of the essay is completed, it needs to be revised repeatedly. Look at whether the beginning is concise and to the point, whether the arguments are typical and true, whether the argument is logical, whether the arguments are novel and consistent, whether the paragraphs are connected naturally, whether the language is smooth and accurate, etc. After you have made the changes, ask your classmates and teachers to help you revise them and gradually improve them. Finally, make a clear copy and send it to newspapers and periodicals for publication or participate in short essay competitions at all levels.

3. Experimenting is my favorite way of entertainment. I often go to bookstores

to read some books about doing experiments, and then go home and do experiments from memory.

On this day, I came to the bookstore again and suddenly discovered a strange experiment: dancing matches. Would you believe that a bare match can dance in the water? I can't believe it. I returned home with a curious heart, ready to use experiments to solve the mysteries in my heart.

When I got home, as usual, I started the experiment from memory.

I first brought a basin of water, then a match and a bottle of "universal glue". I applied a thick layer of "all-purpose glue" on the match head, and then carefully put the match into the water. After waiting for a while, there was no response. I calmed down and waited patiently. A few more minutes passed. The "miracle" really happened! I saw the match standing upright in the water, swaying and dancing. However, within half a minute, the match floated on the water again. After a few minutes, the match started dancing again. This cycle continued seven or eight times, and the match stopped moving.

What magical power drives matches to "dance"? My mind is full of doubts, and I can't figure it out no matter how hard I think about it. In the end, my silent teacher, the computer, helped me. It turns out that when "all-purpose glue" comes into contact with the phosphorus on the match head, a substance will be produced. The more this substance gathers, the more it will make the match stand upright. When this substance evaporates, the match will be driven to "dance" "Get up. After a while, the substance produced on the outside of the match head has evaporated, and the match will not move. After a while, the substance produced gathers again, and the match "dances" again until the super glue and The phosphorus reaction ends.

At this moment, I suddenly realized: Ah! Match sticks can dance, so that’s what it’s like