【正文】 小學(xué)階段的測量主要是線段的長度、圖形的面積、物體的體積，教材把測量的內(nèi)容與圖形的認(rèn)識有機(jī)結(jié)合起來，能提高復(fù)習(xí)的效率。 總復(fù)習(xí)的內(nèi)容也按四個領(lǐng)域編排。圖形的放大和縮小是小學(xué)數(shù)學(xué)新增加的教學(xué)內(nèi)容，讓學(xué)生初步了解圖形可以按一定的比例發(fā)生大小變換。對于轉(zhuǎn)化思想，學(xué)生在前面的學(xué)習(xí)中已經(jīng)有較豐富的體驗(yàn)。這些知識有助于理解圖形的放大與縮小，能用來解決有關(guān)比例尺的問題。是本冊教材的重點(diǎn)內(nèi) 容之一。在前二個單元里教學(xué)新知識，全面完成《標(biāo)準(zhǔn)》規(guī)定的第二學(xué)段的教學(xué)內(nèi)容和具體目標(biāo)。在總復(fù)習(xí)里重點(diǎn)地系統(tǒng)復(fù)習(xí)小學(xué)階段教學(xué)的主要知識，在深化理解的同時組織更合理的認(rèn)知結(jié)構(gòu)，通過適當(dāng)?shù)木毩?xí)形成必要的技能，應(yīng)用知識解決實(shí)際問題，培養(yǎng)數(shù)學(xué)素養(yǎng)。教學(xué)正比例和反比例，著重理解正比例的意義和反比例的意義，讓學(xué)生在現(xiàn)實(shí)的情境中作出相應(yīng)的判斷。在解決問題的策略里，教學(xué)轉(zhuǎn)化的思想和方法。本冊 教材繼續(xù)教學(xué)轉(zhuǎn)化，讓學(xué)生進(jìn)一步體會和應(yīng)用，通過具體的轉(zhuǎn)化活動，發(fā)展思維的靈活性。這個內(nèi)容安排在第三單元里，結(jié)合比例的知識進(jìn)行教學(xué)。根據(jù)《標(biāo)準(zhǔn)》里具體目標(biāo)的設(shè)計(jì)分類，在 “ 數(shù)與代數(shù) ”領(lǐng)域里把內(nèi)容分成數(shù)的運(yùn)算、數(shù)的認(rèn)識、式與方程、正比例與反比例四個部分進(jìn)行復(fù)習(xí)。 “ 統(tǒng)計(jì)與概率 ” 領(lǐng)域的內(nèi)容分統(tǒng)計(jì)、可能性兩個部分進(jìn)行復(fù)習(xí)。 “ 空間與圖形 ” 領(lǐng)域里的內(nèi)容分圖形的認(rèn)識、圖形的變換、圖形的位置 三個部分進(jìn)行復(fù)習(xí)。教材嚴(yán)格遵照《標(biāo)準(zhǔn)》的要求，精選傳統(tǒng)小學(xué)數(shù)學(xué)里有關(guān)形體的知識，增加與生活密切聯(lián)系的空間知識，讓學(xué)生在獲得必需的數(shù)學(xué)事實(shí)的過程中發(fā)展空間觀念。圓柱與圓錐是本冊教材的又一個重點(diǎn)內(nèi)容，包括圓柱和圓錐的形狀特征，圓柱的表面積及計(jì)算方法，圓柱和圓錐的體積及計(jì)算方法等知識。所以，轉(zhuǎn)化是重要的認(rèn)知策略，也是常用的解決問題策略。比例的知識有比例的意義、比例的基本性質(zhì)和解比例。 “ 數(shù)與代數(shù) ” 領(lǐng)域：比例的有關(guān)知識，成正比例和成反比例的量，解決問題的策略。any longer. However, this reali ty al so worri ed m y desi gners. As ti me went by, I was m ade sm al er . First as a PC(personal puter)and then as a l aptop, I have been used i n offi ces and hom es si nce the 1970s. These changes onl y becam e possi bl e as m y m em ory im proved. First i t was stored in tubes,then on transistors and l ater on very sm al chi ps. As a resul tI total y changed m y shape . As I have grown ol der I have also grown sm al l er . Over tim e m y m em oryhas devel oped so m uch that , li ke an el ephant, I never frt anythi ng I have been tol d !And my memory became so large that even I couldn’t believe it!But I was always so lonely standing there by myself,until in the 1960s they gave m e a fami l y connected by a work . Iwas abl e to share m y knowl edge wi th others through the Worl d Wi de Web. Si nce the 1970s m any new appli cati ons have been found for m e . I have bee very i mportant i n m uni cati on, fi nance and trade I have al so been put i nto robots and used to m ake m obi le phones as wel l as hel p with m edical operati ons. I have even been put i nto space rockets and sent to expl ore the Moon and Mars . A nyhow, m y goal i s to provi de hum ans wi th a li fe of hi gh quali ty. I am now trul y fi l ed wi th happi ness that I am a devoted fri end and hel per of the human race ! AN DY—TH E AN DRO ID I’m part of an an android football team . About once a year we are allowed to get together to play a game of footbal. I’m as big as a human . In fact ,I look like one the fotbalteam I’m a striker so I have to be able to run very fast .My puter chips help me to mova and thi nk li ke a hum an . For exam pl e , I have l earned to si gnal to m y team m ates i n puter languages to give m e the bal when I am open and have a good shot for a goal . My fi rat footbal peti ti on was i n N agoya , Japan several years ago . Last year our team went to Seattl e , Washi ngton i n the won tsecong pl ace . Personal y , I thi nk the team that won fi rsy pl ace cheated . They had devel oped a new type of program just before the peti ti on. So we need to encourage our programer to i m prove our i ntel i gence are determi ned to create an even better system . In a way our programm et i s li ke our coach. She program s us wi th m oves to use i f a new sitati on ari ses. In thi s way I can make up new moves using my “artifical intelligence “. I would really like to play against a human team, for I have been programm ed to act just li ke them . After al l, with the hel p of m y el ectroni c brai n whi ch never fets anything ,using my intelligence is what I’m all about! TH E SPO RTIN G RO BO T My nam e is H ua Fei and I am a sporti ng robot of the 23rd century. I am an expert at hi gh flyi ng exerci ses. I jum p from spaceshi p and as I fal I turn, di ve, circl e and dance unti l I softl y l and as close as I can to the fi ni shi ng li ne. Robot peti ti ons i n the 23rd century are truly a popul ar sport. Fans from al l over Chi na watch thei r handhel d TVs when a peti ti on es on. Last tim e I l ook part i n the 78th Ol ym pi c on a fl yi ng i sl and above Brussel s i n the sky. I won the si ver medal for my perform ance . This year I had the honour to be chosen again . I wanted to mm et robots from other countyi es and expl ore i des about our ower , m y programm er fel l il l the week before we were goi ng to l eave . It was very pai nful for her and I fel t very fri ghtened. I no l onger fel t so confi dent that I woul d wi n. The day of the peti ti on was rather coul d for m y l egs and m y speci al oi l began to fteeze. I paused before I jum ped from the starting pl ace on a l i tl e spaceshi p but then I began m y perform ance. At the correct m om ent I tri ed to open m y parachute but there was a probl em . It onl y opened a l ittl e .In stead of fl yi ng softly to earth I began to fal faster and faster so that I coul d not turn , dive, ci rcl e or heart stopped beati ng as I l anded heavi l y on a m ountai n covered wi th snow. Thi s is why I am wri ti ng to you from m y hospital bed wi th two broken l egs and a fragi l e head. I di d not wi n anything at the O l ym pi c after al . I need the factory to bui l d m e two new legs and an even bigger head. Then I wil be able to pete once more . Let’s hope foe greater sucess in the next Olym pi cs! Uni t 4 (1) H ow Daisy l earned to hel p wil dli fe Dai sy had al ways longed to hel p endangered speci es of wil dli fe. O ne day she woke up and found a fl ying carpet by her bed. “Where do you want to go?”it asked. Daiasy responded immediately.“I’d like to see some endangered wildlife,”she said.“please take me to a distant land where I can find the animal that gave fur to make this sweater. ”At once the carpet flew away and took her to Tibet. There Daisy saw an antelope looking sad. It said,“We are being killed for the wool beneath our stomachs. O ur fur i s bei ng used to make sweaters for peopl e l ike you . As a reasul t, we are now an endangered species.”At that Daisy cried,“I’m sorry I didn’t know that. I wonder what is being done to help you. Fly