等式性質(zhì)與不等式性質(zhì)是高中數(shù)學(xué)的主要內(nèi)容之一,在高中數(shù)學(xué)中占有重要地位,它是刻畫現(xiàn)實(shí)世界中量與量之間關(guān)系的有效數(shù)學(xué)模型,在現(xiàn)實(shí)生活中有著廣泛的應(yīng),有著重要的實(shí)際意義.同時等式性質(zhì)與不等式性質(zhì)也為學(xué)生以后順利學(xué)習(xí)基本不等式起到重要的鋪墊.課程目標(biāo)1. 掌握等式性質(zhì)與不等式性質(zhì)以及推論,能夠運(yùn)用其解決簡單的問題.2. 進(jìn)一步掌握作差、作商、綜合法等比較法比較實(shí)數(shù)的大小. 3. 通過教學(xué)培養(yǎng)學(xué)生合作交流的意識和大膽猜測、樂于探究的良好思維品質(zhì)。數(shù)學(xué)學(xué)科素養(yǎng)1.數(shù)學(xué)抽象:不等式的基本性質(zhì);2.邏輯推理:不等式的證明;3.數(shù)學(xué)運(yùn)算:比較多項(xiàng)式的大小及重要不等式的應(yīng)用;4.數(shù)據(jù)分析:多項(xiàng)式的取值范圍,許將單項(xiàng)式的范圍之一求出,然后相加或相乘.(將減法轉(zhuǎn)化為加法,將除法轉(zhuǎn)化為乘法);5.數(shù)學(xué)建模:運(yùn)用類比的思想有等式的基本性質(zhì)猜測不等式的基本性質(zhì)。
本節(jié)課選自《普通高中課程標(biāo)準(zhǔn)實(shí)驗(yàn)教科書數(shù)學(xué)必修1》5.6.2節(jié) 函數(shù)y=Asin(ωx+φ)的圖象通過圖象變換,揭示參數(shù)φ、ω、A變化時對函數(shù)圖象的形狀和位置的影響。通過引導(dǎo)學(xué)生對函數(shù)y=sinx到y(tǒng)=Asin(ωx+φ)的圖象變換規(guī)律的探索,讓學(xué)生體會到由簡單到復(fù)雜、由特殊到一般的化歸思想;并通過對周期變換、相位變換先后順序調(diào)整后,將影響圖象變換這一難點(diǎn)的突破,讓學(xué)生學(xué)會抓住問題的主要矛盾來解決問題的基本思想方法;通過對參數(shù)φ、ω、A的分類討論,讓學(xué)生深刻認(rèn)識圖象變換與函數(shù)解析式變換的內(nèi)在聯(lián)系。通過圖象變換和“五點(diǎn)”作圖法,正確找出函數(shù)y=sinx到y(tǒng)=Asin(ωx+φ)的圖象變換規(guī)律,這也是本節(jié)課的重點(diǎn)所在。提高學(xué)生的推理能力。讓學(xué)生感受數(shù)形結(jié)合及轉(zhuǎn)化的思想方法。發(fā)展學(xué)生數(shù)學(xué)直觀、數(shù)學(xué)抽象、邏輯推理、數(shù)學(xué)建模的核心素養(yǎng)。
地球一小時(Earth Hour)是世界自然基金會(WWF)應(yīng)對全球氣候變化所提出的一項(xiàng)倡議,希望家庭及商界用戶關(guān)上不必要的電燈及耗電產(chǎn)品一小時。來表明他們對應(yīng)對氣候變化行動的支持。過量二氧化碳排放導(dǎo)致的氣候變化目前已經(jīng)極大地威脅到地球上人類的生存。公眾只有通過改變?nèi)蛎癖妼τ诙趸寂欧诺膽B(tài)度,才能減輕這一威脅對世界造成的影響。地球一小時在3月的最后一個星期六20:30~21:30期間熄燈?;顒佑蓙恚骸暗厍?小時”也稱“關(guān)燈一小時”,是世界自然基金會在2007年向全球發(fā)出的一項(xiàng)倡議:呼吁個人、社區(qū)、企業(yè)和政府在每年三月最后一個星期六20:30~21:30期間熄燈1小時,以此來激發(fā)人們對保護(hù)地球的責(zé)任感,以及對氣候變化等環(huán)境問題的思考,表明對全球共同抵御氣候變暖行動的支持。這是一項(xiàng)全球性的活動,世界自然基金會于2007年首次在悉尼倡導(dǎo)之后,以驚人的速度席卷全球,大家都來參加這個活動。[1] “地球1小時”活動首次于2007年3月31日在澳大利亞的悉尼展開,一下子吸引了超過220萬悉尼家庭和企業(yè)參加;隨后,該活動以驚人的速度迅速席卷全球。在2008年,WWF(中國)對外聯(lián)絡(luò)處透露,全球已經(jīng)有超過80個國家、大約1000座城市加入活動。2013年,包括悉尼歌劇院、帝國大廈、東京塔、迪拜塔、白金漢宮在內(nèi)的各國標(biāo)志性建筑也在當(dāng)?shù)貢r間晚八點(diǎn)半熄燈一小時。[2] ,其中包括巴勒斯坦、法屬圭亞那、加拉帕戈斯群島、盧旺達(dá)、圣赫勒那島、蘇里南、突尼斯等首次參與“地球一小時”的國家和地區(qū)。在中國,北京鳥巢、水立方、世貿(mào)天階等標(biāo)志性建筑同時熄燈,同一時段,從上海東方明珠到武漢黃鶴樓,從臺北101到香港天際100觀景臺,中國各地多個標(biāo)志性建筑均熄燈一小時,全國共有127個城市加入“地球一小時”活動。
The topic of this part is “Write about your festival experience”.During the Listening and Speaking and Talking, students are just asked to say out their festival experiences such as the Spring Festival, Mid-autumn Day, but this part students will be asked to write down their own festival experiences. During the reading part, it introduces the Naadam Festival in Inner Mongolia Autonomous Region, which can give students a good example to imitate. Students not only learn the festival, but touch and feel the Inner Mongolian’s character, the spirit and cultural atmosphere, which can help students form the cultural awareness and learn to enjoy and value the diversity of Chinese culture.Concretely, the dairy tells the experience that the author spent the Naadam Festival in Inner Mongolia Autonomous Region with his/her friend. The structure is clear. In the opening paragraph, it introduces the topic of the Naadam Festival and the whole feeling. Then it introduces the items of the festival like the ceremony, wrestling and horse racing. Finally, it summarizes this experience. Because this part is a travel journal, we must guide students pay more attention to these details: 1. use the first person. 2. use the past tense to tell the past thing and use the present or future tense to describe the scenery. 3. use the timeline to tell the development. 4. be careful for the author’s psychology, emotion and feeling, etc.1. Read quickly to get main idea; read carefully to get the detailed information about Naadam Festival.2. Learn the structure of the reading article and language.3. Write an article about a festival experience4. Learn to use the psychology, emotions and feeling in the writing.1. Write an article about a festival experience.2. Use the structure of the reading article and language.
Listening and Speaking introduces the topic of “talking about how to become an astronaut”. This period is aimed to inform students some details about the requirements of being an astronaut. Students can be motivated and inspired by the astronauts. Teachers ought to encourage students to learn from them and let them aim high and dream big.Listening and Talking introduces the theme of "talk about life in space". This part also informs students more details about life in space and can inspire students to be curious about this job. 1. Guide students to listen for numbers concerning dates, years and ages etc2. Cultivate students' ability to talk about how to become an astronaut and life in space ; 3. Instruct students to use functional sentences of the dialogue such as “ first of all, I am not sure, so what might be .. I guess.. I wonder…I am curious…)appropriately.1. Guide students to understand the content of listening texts in terms of the whole and key details; 2. Cultivate students' ability to guess the meaning of words in listening; discuss with their peers how to become a qualified astronaut and describe the life in space.Part 1: Listening and SpeakingStep 1: Lead inPredictionThe teacher can ask students to predict what the listening text is about by looking at the pictures.About how to become an astronaut./the requirements of an astronautStep 2: Then, play the radio which is about an interview a. And after finishing listening for the first time, the students need to solve the following tasks.
Q4: What is the function of the International exploration ?Having astronauts from different countries on boardQ5: What can you learn from Para 4 ?China has made great achievements in exploring spaceQ6: What is the attitude to the space exploration ?SupportiveStep 6 Post reading---RetellPeople have always wanted to learn more about space. Before the mid-20th century, most people felt (1)_________ (travel) into space was an impossible dream. However, (2)____ the help of scientists, peoplesucceeded in realizing their dream (3) _________ (explore) space. On 4 October 1957, the Sputnik 1 satellite (4) ____________(launch) by the USSR. (5) ________________ scientists try to make sure nothing goes wrong, accidents can still happen. These disasters made everyone(6)___________(disappoint), but people still believe in the importance of (7) ________(carry) on space exploration. In 2003, China became the third country to (8)_____________ (independent) send humans into space. Then Shenzhou 6 and 7 completed (9)____ second manned orbit and the first Chinese spacewalk. In spite of the difficulties, scientists hope future (10)__________ (discovery) will not only enable us to understand the universe but also help us survive well into the future.Answers: 1. travelling 2. with 3. to explore 4. was launched 5. Although6. disappointed 7. carrying 8. independently 9. a 10. discoveriesStep 6 Post reading---Critical thinkingQ1: What do you think of the space exploration ? I think it is beneficial to us. Through further study of space, people will make full use of it in the future, such as the space experiments by Wang Yaping in Tian Gong 1.Q2: If you are determined to be an astronaut, what should you prepare at present ?First of all, I should study hard to get a related college degree. Besides, I must keep mental and physical healthy.Step 7. HomeworkTry to summarize the structure of the article by a mind map.
另一方面,其余的人反對這個計(jì)劃,因?yàn)樗赡軙?dǎo)致一些不好的影響。7.I hold the belief that space exploration not only enable us to understand how the universe began but also help us survived well into the future.我堅(jiān)信探索太空不僅能夠使我們了解宇宙的起源而且能夠幫助我們更好地走進(jìn)未來。8.I think we should spend more time and money exploring space so as to provide new and better solutions to people's shortterm and longterm problems.為了給人類的短期和長期問題提供更新和更好的解決方法,我認(rèn)為我們應(yīng)該花更多的時間和金錢來探索太空。9.From my point of view,it is wrong of young people to depend on their telephones too much,which may do harm to both their physical and mental health.在我看來,年輕人過度依賴手機(jī)是不對的,因?yàn)樗鼈兛赡軙λ麄兊纳硇慕】刀加泻?。最近你班同學(xué)就“人類是否應(yīng)該進(jìn)行宇宙探索”這個問題進(jìn)行了激烈的討論。有人認(rèn)為,探索宇宙不僅讓人類更好地了解宇宙的發(fā)展,還可以用來指導(dǎo)農(nóng)業(yè)生產(chǎn),以及把一些探索太空的高新技術(shù)用于現(xiàn)實(shí)生活;也有一些人認(rèn)為探索太空花掉了大量的人力物力;影響了人們的生活水平。請你根據(jù)以下情況寫一篇報告并發(fā)表自己的觀點(diǎn)。注意:1.寫作內(nèi)容應(yīng)包括以上全部要點(diǎn),可適當(dāng)發(fā)揮,使上下文連貫;
Everybody wants to get wealth.In today’s material world,making money or becoming wealthy symbolizes a person’s success and capability. Many people just make every effort, pay any price to attain greater wealth. With money,they can buy nice, large apartments in nice neighborhood. With money they can own luxurious cars. Wealth seems to bring all happiness in life.But is wealth the only road to happiness? Not really. There are many things in the world, which are beyond the means of money, such as friendship, love, health and knowledge. People are so preoccupied with struggling for money that they have no time or would not take the time to form or maintain friendship. What happiness can they feel living as lonely miserable creatures without love or friends in the world even if they accumulate tremendous wealth?In my opinion, people can’t do anything without money, but money is not everything. What money will bring you depends on your personal belief and goal in life. If you are kind enough to help others, especially the poor, money is a good thing to you. With it, you can do much more for the benefit of people and your country, and it will add to your own happiness. If you want money just for your own needs, you’ll never be satisfied or happy. In a word,you should have money spent for more people. Only then can money be the source of your happiness.Step 8 Homework4 students in a group, one acts Roderick, one Oliver, one servant and the fourth one acts Henry Adams, then listen to the tape, pay more attention to the difference between American English and British English in pronunciation, stress, tone.
【參考范文】Narrator:(Henry is smiling as he leaves the restaurant. As he is walking down the street, he sees a sign for a place that cuts hair. He decides to get it cut. )H=Henry;B=Barber;R=rude manH:Good afternoon, I'd like to get a cut, if I may. (The barber looks at Henry's hair and continues cutting another man's hair. )Er, I'd really like a haircut. As you can see it's much too long. B:(in a rude manner) Yes, I can see that. Indeed, I can. H:Fine, well I'll have a seat then. (He sits in one of the barber's chairs. The barber turns to look at Henry. )B:It's quite expensive here, you know!Are you sure you can afford it?H:Yes. I think so. (In comes the rude man. )R:Hey you there. I need a haircut quickly. Can you do me straightaway?B:All right, then, get in the chair and I'll see what I can do. R:Thank you. (sits down in one of the barber's chairs)H:Excuse me, but I was here first. Aren't you going to do my hair first?B:This man's in a hurry. H:Well so am I!I insist that you cut my hair first. B:OK, but I'll have to be quick. This gentleman is waiting. H:Thank you. (They both become quiet. After his hair is cut, the barber tells Henry how much he must pay. Henry shows the barber the bank note. )B:Why, Mr . . . (looks shocked)H:Adams. Henry Adams. I'm sorry, I don't have any change. R:You're that Mr Adams! Well,I'm glad I waited or I might never have known it was you. B:Why, Mr Adams, please don't worry!(wearing a big smile) Nothing to worry about!Nothing at all!Please come back any time, even if you only need too little hairs cut!It will be my honour to serve you!
2、從周圍生活中發(fā)現(xiàn)多種有趣的數(shù)字,初步了解數(shù)字在生活中的實(shí)際意義?! 』顒訙?zhǔn)備: 1、幼兒收集的有數(shù)字的物品; 2、電腦課件(打電話的情景) 3、英語兒歌 活動過程: 一、英語兒歌引出?! ?提問:說說這首兒歌里有哪些數(shù)字? 二、介紹生活中有數(shù)字的物品?! ?你收集的材料上有哪些數(shù)字,它們有什么作用? (在此進(jìn)行提升幼兒對數(shù)字的認(rèn)識,如:食品袋上的數(shù)字代表生產(chǎn)日期、保質(zhì)期;藥瓶上不僅有保質(zhì)期,而且還有劑量等。我們生活中處處有數(shù)字,數(shù)字用處很大。它可以表示順序、日期、時間等。如果沒有數(shù)字,生活就會變得亂糟糟,甚至還會出事故呢?。?/p>
活動準(zhǔn)備: 1、森林背景圖,6張蘑菇房子圖片?! ?2、1-6的大點(diǎn)卡和數(shù)卡一套。 3、小猴、小兔頭飾各一個和老虎的圖片一張 4、幼兒數(shù)學(xué)操作板1個/人,1-6的點(diǎn)卡一套/人?! ?5、標(biāo)有1—6的數(shù)字卡片,每個小朋友一張 6、故事《住賓館》?! 』顒舆^程: 一、開始部分:初步理解“鄰居”關(guān)系?!?1、拍手游戲:“嘿嘿,ⅹⅹⅹ(小朋友名),我問你,你的朋友在哪里?”“嘿嘿嘿,在這里!”(被問的小朋友舉起旁邊小朋友的手。) 2、我們每個小朋友都有自己午休的小床,請你說一說自己的鄰居都有誰,讓幼兒理解什么是鄰居。
2、愛自己的家,樂于幫助爸爸媽媽招待客人?! ?3、能獨(dú)立完成操作活動?! ?活動準(zhǔn)備: 筷子若干雙,托盤一個(內(nèi)裝有小包裝的糕點(diǎn)若干),碟子3-5個(邊上分別貼有一張7以內(nèi)的數(shù)卡);實(shí)物展示儀。幼兒用書,幼兒人手一支筆;1-7的數(shù)字印章、印泥若干?! ?活動過程: 一、我?guī)蛬寢寠A花生。 教師:今天爸爸媽媽邀請了朋友來做客,你是家里的小主人,可以幫爸爸媽媽做些什么事呢? 鼓勵幼兒提出幫助父母整理家里的物品,招待客人?! ?教師(出示貼有數(shù)卡的碟子):客人來了,爸爸媽媽要邀請客人吃點(diǎn)心。你知道客人想吃幾個點(diǎn)心呢?你是怎么知道的? 教師(出示裝有花生的托盤):誰愿意幫客人拿點(diǎn)心?請個別幼兒示范拿點(diǎn)心,鼓勵幼兒看清卡上的數(shù)字,邊拿邊數(shù)。 教師將幼兒裝有點(diǎn)心的小放在視頻展示儀下面,師幼共同檢查花生的數(shù)量和數(shù)卡是否一致。
活動目標(biāo):1、通過一系列的游戲活動,讓幼兒認(rèn)識序數(shù)第一至第五。2、發(fā)展幼兒思維的邏輯判斷能力。活動準(zhǔn)備:數(shù)字卡片、小旗人手一套、房子(紅、黃、藍(lán)、綠、紫)、小動物圖片、高樓一棟、記錄表活動流程:找房子→舉小旗→動物找家→幼兒操作活動過程:一、讓幼兒學(xué)會用第幾座的形式來表示不同顏色的房子分別在第幾座。 1、師:好消息,好消息!森林小區(qū)要搬遷啦!小動物們請我們?nèi)兔Γ覀兛斐霭l(fā)吧!看,森林里有許多不同顏色的小房子,它們分別是什么顏色?(紅、藍(lán)、紫、綠、黃)一共有幾座?(5座)你是怎么數(shù)的?(幼兒自由發(fā)揮/從左往右)2、師:紅房子在第幾座?3、幼兒回答:第1間。
2、仔細(xì)觀察,大膽想象,提高思維的靈活性。 3、體驗(yàn)數(shù)學(xué)游戲的快樂,增強(qiáng)參與數(shù)學(xué)活動的自信心。活動準(zhǔn)備: 雪花片每桌一份,幼兒人手一張數(shù)字卡,桌面各貼一個數(shù)字(1-7),教師數(shù)字卡1—7,塑料花若干,小樹、小花、水梨、葡萄數(shù)量各為八個?;顒舆^程:1、復(fù)習(xí)鞏固7以內(nèi)的數(shù):(1)、-----師出示塑料花,引起幼兒種花樹的興趣,幼兒變魔術(shù)成為小花樹,教師變成魔術(shù)師。------魔術(shù)師:“小花樹們按照你們手里的數(shù)字,去找相應(yīng)的花盆(桌子),把自己種下去!”------幼兒按照自己手中的數(shù)字尋找正確的位置?!癤XX花寶寶你種 在幾號花盆里???” (2)、游戲:《花開花落》 師:“小花樹在太陽公公和雨姑姑的照顧下,開出了X朵花!” 幼兒根據(jù)教師出示的數(shù)字卡片,拿相應(yīng)數(shù)量的雪花片。 (師逐一出示數(shù)字卡2、3、4。)
二、通過情景游戲等活動,讓幼兒初步感知圖形之間的轉(zhuǎn)換關(guān)系,并能想辦法解決問題。三、培養(yǎng)幼兒思維的靈活性,發(fā)展幼兒動手能力,激發(fā)幼兒學(xué)習(xí)數(shù)學(xué)的欲望。活動準(zhǔn)備:1、學(xué)會了各種圖形的特征。2、自制的“小路”,上面鏤刻大小不同的圖形“土坑”,將鏤刻下來的圖形作成鋪路的“石頭”。小籃同幼兒人數(shù)。3、圓形、三角形、長方形、正方形的圖形標(biāo)記,音樂。活動過程:一、情景導(dǎo)入“撿石頭”,激發(fā)幼兒活動興趣。1、“小朋友,今天的天氣真好,我們一起去郊外撿石頭!”(隨音樂進(jìn)入活動室)2、教師提出操作要求:“快看!有那么多五彩繽紛的小石頭,大家可以挑自己喜歡的撿?!?、引導(dǎo)幼兒觀察、操作,鼓勵幼兒邊操作邊交流。4、請小朋友大膽介紹自己喜歡的石頭(顏色、形狀)。5、游戲:按標(biāo)記舉“石頭”。
2、了解小樹的生長過程,有初步的邏輯判斷能力。 活動準(zhǔn)備: 1、幼兒認(rèn)識數(shù)字1—4,有初步目測4以內(nèi)數(shù)的經(jīng)驗(yàn)?! ?2、學(xué)具:相冊模板16個,相應(yīng)圖片16套;教具:相冊、照片范例?! ?活動過程: 1、導(dǎo)入,引起幼兒興趣。 (1)師:樹媽媽給樹寶寶拍了許多照片,你們想看嗎? 師:我們來看看,它都給小樹拍了哪些照片。 (2)出示小樹相片,幼兒感受照片上小樹的不同數(shù)量和不同的生長階段?! ?①出示“小芽”的照片。 師:這是樹寶寶的照片嗎?是樹寶寶什么時候的照片? 師:小的時候它叫什么呢? (引導(dǎo)幼兒說出小芽) 師:這是小樹在小芽時候的照片,是幾個小芽?(目測小芽的數(shù)量)
2、通過品嘗餅干、觀察餅干、觸摸餅干,感知形狀的基本特征,大膽想象其他圓形、正方形、三角形的物體?! ?3、在活動中愿意大膽的講述。 活動準(zhǔn)備: 1、教具: ——圓形、三角形、正方形的餅干若干,放置托盤中,并用蓋布蓋住?! ?——圓形、三角形、正方形圖片各一個?!? 2、學(xué)具 ——幼兒操作材料每人一份,彩色筆若干。 ——各種類似圓形、三角形、正方形的物品,例如:圓盤子、書、三角鐵、鏡子、積木、三角尺、插花等,散放在活動室的四周。
2、繼續(xù)學(xué)習(xí)正確目測6以內(nèi)的數(shù)群。 3、樂意主動的講述自己的操作過程和結(jié)果?! 』顒訙?zhǔn)備: 1、教具:分類底版,6以內(nèi)的實(shí)物卡片,相應(yīng)數(shù)量的數(shù)卡 2、學(xué)具:超市售貨員(分類底版,6以內(nèi)的各種實(shí)物卡片,相應(yīng)數(shù)(點(diǎn))卡等),給一樣多的發(fā)花(不同排列形式的實(shí)物操作卡,雪花片),一樣多的放一起(6以內(nèi)不同排列形式的實(shí)物卡片) 活動過程: 1、游戲?qū)?,了解游戲玩法? (1)出示分層式分類底版,各種球類實(shí)物卡。 教師:超市里有許多的球,讓我們看看有哪些球呢?它們各是幾個?你是怎么看出來的?引導(dǎo)幼兒用目測的方法數(shù)數(shù),并能說一說自己數(shù)的方法。 ?。?)師幼共同討論整理“分層貨架”的規(guī)則:一樣多的球放在一起
2、發(fā)展幼兒思維的邏輯判斷能力。3、愿意參加游戲活動,體驗(yàn)游戲的樂趣?;顒訙?zhǔn)備:1、學(xué)具:小旗人手一套。2、教具:大數(shù)卡一套、房子五座、小旗一面、五種小動物活動過程: 一、用第幾座的形式表示不同顏色的房子分別在第幾座1、出示房子提問:他們分別是什么顏色?(紅、黃、藍(lán)、綠、紫)一共有幾座?紅房子在第幾座?你是從哪邊開始數(shù)的?有不一樣的嗎?2、出示小旗提問:現(xiàn)在,我們從哪邊開始數(shù)?3、做門牌卡:紅房子在第一座,用數(shù)字幾表示?(請幼兒找數(shù)字貼在房頂上)
2、認(rèn)識圓形、正方形、三角形圖形標(biāo)記,并學(xué)習(xí)按照圖形標(biāo)記制作相應(yīng)的形狀?! ?、能注意操作過程中的書面整潔,樂意邊操作邊講述。 活動準(zhǔn)備: 1、圓形、三角形、正方形餅干(均未拆封)若干。 2、三只毛絨小動物,每個小動物胸口有一個形狀標(biāo)記?! ?、圓形、三角形、正方形大圖片?! ?、幼兒用書(P10—11)人手一冊 5、圓形、三角形、正方形的印章(或小圖片),顏料等若干?! 』顒舆^程: 一、觀察餅干的形狀,了解形狀的主要特征。1、出示餅干,請幼兒說說:這是什么?它有哪些形狀?你喜歡吃什么形狀的餅干? 2、教師(出示圓形、三角形、正方形):圓形(三角形、正方形)是什么樣子的? 3、教師折疊圖形,引導(dǎo)幼兒直觀感受圖形的特征呢感,使幼兒知道:圓形是圓圓的,沒有尖尖的角;正方形有四個一樣大的角,一樣長的邊;三角形有三個角,三條邊。