新人教版一年级数学上册第八单元复习教案

教案标题：第八单元解决问题（1）教学目标：1. 让学生掌握简单的加减法运算，能够解决实际问题。

2. 培养学生运用数学知识解决生活问题的能力。

3. 培养学生的观察力、思考力和合作意识。

教学重点：1. 理解并掌握加减法运算。

2. 能够运用加减法解决实际问题。

教学难点：1. 理解加减法运算的含义。

2. 解决实际问题时，能够正确运用加减法运算。

教学准备：1. 教师准备：课件、教具（如图片、卡片等）。

2. 学生准备：课本、练习本、铅笔。

教学过程：一、导入（5分钟）1. 教师出示一张图片，图片上有5个苹果，然后又拿出3个苹果放在旁边，问学生：“现在一共有多少个苹果？”2. 学生回答：“5 3=8个苹果。

”3. 教师总结：“今天我们要学习的就是这种简单的加减法运算，它可以帮助我们解决很多实际问题。

”二、新课导入（15分钟）1. 教师出示一张图片，图片上有7个气球，然后又拿出2个气球放在旁边，问学生：“现在一共有多少个气球？”2. 学生回答：“7 2=9个气球。

”3. 教师总结：“当我们知道两个数的和时，我们可以通过减法运算来求出其中一个数。

比如，我们知道9个气球，去掉2个气球，还剩下多少个气球？”4. 学生回答：“9-2=7个气球。

”三、巩固练习（10分钟）1. 教师出示一张图片，图片上有10个橘子，然后又拿出4个橘子放在旁边，问学生：“现在一共有多少个橘子？”2. 学生回答：“10 4=14个橘子。

”3. 教师总结：“当我们知道两个数的和时，我们可以通过减法运算来求出其中一个数。

比如，我们知道14个橘子，去掉4个橘子，还剩下多少个橘子？”4. 学生回答：“14-4=10个橘子。

”四、拓展提高（10分钟）1. 教师出示一张图片，图片上有6个铅笔，然后又拿出3个铅笔放在旁边，问学生：“现在一共有多少个铅笔？”2. 学生回答：“6 3=9个铅笔。

”3. 教师总结：“当我们知道两个数的和时，我们可以通过减法运算来求出其中一个数。

人教版小学一年级数学上册第八单元《20以内的进位加法》教案一. 教材分析《20以内的进位加法》是人教版小学一年级数学上册第八单元的内容，主要让学生掌握加法的基本运算方法，学会将两个数相加，并能够进行20以内的进位加法运算。

教材通过例题和练习，使学生熟练掌握进位加法的运算规律，培养学生的运算能力和逻辑思维能力。

二. 学情分析一年级的学生已经具备了一定的数数能力，对加法运算有一定的认识。

但在实际操作中，可能对进位加法的运算规律还不够熟练，需要通过大量的练习来巩固。

此外，学生的学习兴趣和积极性也需要被激发和保持。

三. 教学目标1.让学生掌握20以内的进位加法运算方法。

2.培养学生的运算能力和逻辑思维能力。

3.激发学生的学习兴趣，提高学生的学习积极性。

四. 教学重难点1.教学重点：让学生掌握进位加法的运算规律。

2.教学难点：如何引导学生理解和掌握进位加法的运算过程。

五. 教学方法采用情景教学法、游戏教学法和小组合作学习法。

通过设定情景，让学生在实际操作中学习进位加法；通过游戏，激发学生的学习兴趣，巩固所学知识；通过小组合作学习，培养学生的团队协作能力和沟通能力。

六. 教学准备1.教学PPT：包括教材中的例题和练习题。

2.教学卡片：用于游戏教学，巩固知识。

3.学习用品：如笔、纸等，供学生练习使用。

七. 教学过程1.导入（5分钟）通过一个简单的加法游戏，引导学生进入学习状态。

例如，教师出示两个数字，让学生快速说出它们的和。

这样的游戏可以激发学生的学习兴趣，同时巩固他们对加法的认识。

2.呈现（10分钟）教师通过PPT呈现教材中的例题，引导学生观察和思考。

例如，出示一个加法算式：3 + 5 = ? 让学生尝试解答。

在学生回答后，教师进行讲解，说明进位加法的运算规律。

3.操练（10分钟）教师让学生进行大量的练习，巩固所学知识。

例如，让学生完成PPT上的练习题，或者发放教学卡片，让学生进行小组内的竞赛。

在学生解答过程中，教师进行巡回指导，帮助学生理解和掌握进位加法的运算过程。

第八单元认识钟表课题：认识钟表(整时)教学内容：教科书第91、92页的内容，教学目的：1、结合生活经验认识钟面，学会看整时。

2、建立时间观念，培养学生养成遵守时间、珍惜时间的良好生活、学习习惯。

3、培养学生的观察能力，能用所学的知识，合理安排自己的时间，做时间的主人。

教学重点：正确读写钟表上的整时。

教学难点：正确、迅速说出钟面时间。

教学过程：一、导入：你的一天是怎样度过的？誰愿意说给大家听？你是怎么知道的？(板书：认识钟表)教师说明：说起钟表，从古至今，从国内到国外，不知道有多少精致美观、造型独特的钟表。

下面我们就来欣赏一部分钟表作品，好不好？二、主动探索1、制作钟表(1)欣赏完了这么多美丽的钟表，你想对大家说点什么？(2)在平时，你们也见过许多钟表，现在，就请你们闭上你们的眼睛，静静地想一想：钟面上都有些什么？(放音乐伴奏)(3)在每个小组的桌上，有一些制作钟表的工具和材料，你们能用这些工具和材料做一个钟面吗？要求：先小组合作进行制作，做完后，同组的同学认真观察钟面，看一看，钟面上都有些什么，并相互说一说。

(4)有哪个同学愿意代表你们组给大家说说。

(指2人------3人)教师根据的回答进行板书：数字：1、2、3、4、5、6、7、8、……11、12针：分针(长) 时针(短)(5)：把你们制作好的钟面举起来给大家看一看，再拿出你们自己的小闹钟互相说一说哪是时针、哪是分针。

2、认识钟表(1)出示一个钟面时刻：2时提问：有谁认识这个时刻？你是怎么认识的？请把你的方法说给大家听。

(指名2-----3人)(2)再出示四个钟表，请每个小朋友先认一认，再同桌互相说一说，你是怎么认的？最后指名起来认一认，说一说。

(3)象这样的时刻还有一种更简单的写法，有谁见过？指名学生上台试着写一写。

那这四个钟面的简单时刻谁会写？(指名写，全班齐写)3、每个小组在你们制作的钟面上拨一个整点时刻，先拨好就先贴在黑板上。

(指名认，指名写简单写法)三、游戏巩固：1、教师说时刻，学生拨2、同桌互拨，互认3、这么多的时刻中，你最喜欢哪个时刻？为什么？四：设计请每个小朋友做一个小小钟表设计师，设计一个自己最得意的钟表作品。

第八单元20以内的进位加法第1课时9加几【教学内容】：教材P88、P89及练习二十第1-3题【教学目标】：1.通过对问题情境的探索，使学生在已有经验的基础上，自己得出9加几的方法。

2.使学生初步理解“凑十法”，初步了解“9加几”进位加法的思维过程，并能用自己喜欢的方法正确计算9加几的口算。

3.培养学生的观察、合作交流和动手操作能力，以及初步的提出问题、解决问题的能力，发散学生思维，培养创新意识。

4.在学习活动中激发学生学习数学的兴趣。

【教学重点】：能用自己喜欢的方法正确计算9加几的口算。

【教学难点】：使学生在已有经验的基础上，自己得出9加几的方法。

【教具、学具准备】：13根小棒。

【教学过程】：一、创设情境，设疑激趣（P88情境图）小朋友们，十月份是我校的体育节，我们学校不仅举办了盛大的开幕仪式，还举行了全校运动会。

为了给运动员解渴，他们还准备了一些饮料，已经喝了一些，比赛快结束时，小明问：“还有多少盒?”二、新授1.组织学生讨论“一共有多少盒?”的问题。

①小组讨论，交流解决问题的方法。

②组织全班学生交流解决问题的方法。

2.请小组代表向全班学生介绍本组的方法。

根据学生的发言，教师逐一板书各种解决方法。

①数出结果。

从9接着数。

从4接着数。

②推算出结果。

10加4等于14，9比l0少1，所以9加4等于13。

③用“凑十法”计算出结果。

3.理解“凑十法”。

①操作：左边摆9根小棒代表箱子里的9盒饮料，右边摆4根小棒代表箱外的4盒饮料。

演示口算过程。

②教师边提问边指导操作：回忆一下，刚才的同学是怎样移动饮料的?该怎样移动小棒呢?(指名演示)（箱子外面的四盒饮料拿走一盒，还剩几盒?10盒再加上箱子外面剩下的3盒饮料一共是多少盒饮料?所以9加4等于多少?）③问：在这几种方法中你比较喜欢哪一种?4.解决“踢球的和跳远的一共有多少人?”5.引导学生观察画面，问：你还能提出哪些用加法计算的问题?小组讨论后发表意见，解决同学们提出的问题。

土木工程专业英语翻译土木工程专业外语翻译专业：铁道工程学号：20137084姓名：郭翔西南交通大学峨眉校区2016 年 6 月16 日Building construction concrete crack ofprevention and processingAbstractThe crack problem of concrete is a widespread existence but again difficult in solve of engineering actual problem, this text carried on a study analysis to a little bit familiar crack problem in the concrete engineering, and aim at concrete the circumstance put forward some prevention, processing measure. Keyword:Concrete crack prevention processingForewordConcrete's ising 1 kind is anticipate by the freestone bone, cement, water and other mixture but formation of the in addition material of quality brittleness not and all material.Because the concrete construction transform with oneself, control etc. a series problem, harden model of in the concrete existence numerous tiny hole, spirit cave and tiny crack, is exactly because these beginning start blemish of existence just make the concrete present one some not and all the characteristic of quality.The tiny crack is a kind of harmless crack and accept concrete heavy, defend Shen and a little bit other use function not a creation to endanger.But after the concrete be subjected to lotus carry, difference in temperature etc. function, tiny crack would continuously of expand with connect, end formation we can see without the aid of instruments of macro view the crack be also the crack that the concrete often say in the engineering.Concrete building and Gou piece usually all take sewer to make of, because of crack of existence and development usually make inner part of reinforcing bar etc. material creation decay, lower reinforced concrete material of loading ability, durable and anti- Shen ability, influence building of external appearance, service life, severity will threat arrive people's life and property safety.A lot of all ofcrash of engineerings is because of the unsteady development of the crack with the result that.Modern age science research with a great deal of of the concrete engineering practice certificate, in the concrete engineering crack problem is ineluctable, also acceptable in certainly of the scope just need to adopt valid of measure will it endanger degree control at certain of scope inside.The reinforced concrete norm is also explicit provision:Some structure at place of dissimilarity under the condition allow existence certain the crack of width.But at under construction should as far as possible adopt a valid measure control crack creation, make the structure don't appear crack possibly or as far as possible decrease crack of amount and width, particularly want to as far as possible avoid harmful crack of emergence, insure engineering quality thus.Concrete crack creation of the reason be a lot of and have already transformed to cause of crack:Such as temperature variety, constringency, inflation, the asymmetry sink to sink etc. reason cause of crack;Have outside carry the crack that the function cause;Protected environment not appropriate the crack etc. caused with chemical effect.Want differentiation to treat in the actual engineering, work°out a problem according to the actual circumstance.In the concrete engineering the familiar crack and the prevention1.Stem Suo crack and preventionStem the Suo crack much appear after the concrete protect be over of a period of time or concrete sprinkle to build to complete behind of around a week.In the cement syrup humidity of evaporate would creation stem Suo, and this kind of constringency is can't negative.Stem Suo crack of the creation be main is because of concrete inside outside humidity evaporate degree dissimilarity but cause to transform dissimilarity of result:The concrete is subjected to exterior condition of influence, surface humidity loss lead quick, transform bigger, inner part degree of humidity variety smaller transform smaller, bigger surface stem the Suo transform to be subjected to concrete inner part control, creation more big pull should dint but creation crack.The relative humidity is more low, cement syrup body stem Suo more big, stem the Suo crack be more easy creation.Stemthe Suo crack is much surface parallel lines form or the net shallow thin crack, width many between 0.05-0.2 mm, the flat surface part much see in the big physical volume concrete and follow it more in thinner beam plank short to distribute.Stem Suo crack usually the anti- Shen of influence concrete, cause the durable of the rust eclipse influence concrete of reinforcing bar, under the function of the water pressure dint would creation the water power split crack influence concrete of loading dint etc..Concrete stem the Suo be main with water ash of the concrete ratio, the dosage of the composition, cement of cement, gather to anticipate of the dosage of the property and dosage, in addition etc. relevant. Main prevention measure:While being to choose to use the constringency quantity smaller cement, general low hot water mire and powder ash from stove cement in the adoption, lower the dosage of cement.Two is a concrete of stem the Suo be subjected to water ash ratio of influence more big, water ash ratio more big, stem Suo more big, so in the concrete match the ratio the design should as far as possible control good water ash ratio of choose to use, the Chan add in the meantime accommodation of reduce water.Three is strict control concrete mix blend with under construction of match ratio, use of concrete water quantity absolute can't big in match ratio design give settle of use water quantity.Four is the earlier period which strengthen concrete to protect, and appropriate extension protect of concrete time.Winter construction want to be appropriate extension concrete heat preservation to overlay time, and Tu2 Shua protect to protect.Five is a constitution the accommodation is in the concrete structure of the constringency sew.2.The Su constringency crack and preventionSu constringency is the concrete is before condense, surface because of lose water quicker but creation of constringency.The Su constringency crack is general at dry heat or strong wind the weather appear, crack's much presenting in the center breadth, both ends be in the centerthin and the length be different, with each other not coherent appearance.Shorter crack general long 20-30 cm, the longer crack can reach to a 2-3 m, breadth 1-5 mm.It creation of main reasonis:The concrete is eventually almost having no strength or strength before the Ning very small, perhaps concrete just eventually Ning but strength very hour, be subjected to heat or compare strong wind dint of influence, the concrete surface lose water to lead quick, result in in the capillary creation bigger negative press but make a concrete physical volume sharply constringency, but at this time the strength of concrete again can't resist its constringency, therefore creation cracked.The influence concrete Su constringency open the main factor of crack to have water ash ratio, concrete of condense time, environment temperature, wind velocity, relative humidity...etc..Main prevention measure:One is choose to use stem the Suo value smaller higher Huo sour salt of the earlier period strength or common the Huo sour brine mire.Two is strict the control water ash ratio, the Chan add to efficiently reduce water to increment the collapse of concrete fall a degree and with easy, decrease cement and water of dosage.Three is to sprinkle before building concrete, water basic level and template even to soak through.Four is in time to overlay the perhaps damp grass mat of the plastics thin film, hemp slice etc., keep concrete eventually before the Ning surface is moist, perhaps spray to protect etc. to carry on protect in the concrete surface.Five is in the heat and strong wind the weather to want to establish to hide sun and block breeze facilities, protect in time.3.Sink to sink crack and preventionThe creation which sink to sink crack is because of the structure foundation soil quality not and evenly, loose soft or return to fill soil dishonest or soak in water but result in the asymmetry sink to decline with the result that;Perhaps because of template just degree shortage, the template propped up to once be apart from big or prop up bottom loose move etc. to cause, especially at winter, the template prop up at jelly soil up, jelly the soil turn jelly empress creation asymmetry to sink to decline and cause concrete structure creation crack.This kind crack many is deep enter or pierce through sex crack, it alignment have something to do with sinking to sink a circumstance, general follow with groundperpendicular or present 30 °s-45 ° Cape direction development, bigger sink to sink crack, usually have certain of wrong, crack width usually with sink to decline quantity direct proportion relation.Crack width under the influence of temperature variety smaller.The foundation after transform stability sink to sink crack also basic tend in stability.Main prevention measure:One is rightness loose soft soil, return to fill soil foundation a construction at the upper part structure front should carry on necessity of Hang solid with reinforce.Two is the strength that assurance template is enough and just degree, and prop up firm, and make the foundation be subjected to dint even.Three is keep concrete from sprinkle infusing the foundation in the process is soak by water.Four is time that template tore down to can't be too early, and want to notice to dismantle a mold order of sequence.Five is at jelly soil top take to establish template to notice to adopt certain of prevention measure.4.Temperature crack and preventionTemperature crack much the occurrence is in big surface or difference in temperature variety of the physical volume concrete compare the earth area of the concrete structure.Concrete after sprinkling to build, in the hardening the process, cement water turn a creation a great deal of of water turn hot, .(be the cement dosage is in the 350-550 kg/m 3, each sign square the rice concrete will release a calories of 17500-27500 kJ and make concrete internal thus the temperature rise to reach to 70 ℃or so even higher)Because the physical volume of concrete be more big, a great deal of of water turn hot accumulate at the concrete inner part but not easy send forth, cause inner part the temperature hoick, but the concrete surface spread hot more quick, so formation inside outside of bigger difference in temperature, the bigger difference in temperature result in inner part and exterior hot the degree of the bulge cold Suo dissimilarity, make concrete surface creation certain of pull should dint.When pull should dint exceed the anti- of concrete pull strength extreme limit, concrete surface meeting creation crack, this kind of crack much occurrence after theconcrete under construction period.In the concrete of under construction be difference in temperature variety more big, perhaps is a concrete to be subjected to assault of cold wave etc., will cause concrete surface the temperature sharply descend, but creation constringency, surface constringency of the concrete be subjected to inner part concrete of control, creation very big of pull should dint but creation crack, this kind of crack usually just in more shallow scope of the concrete surface creation.The alignment of the temperature crack usually none settle regulation, big area structure the crack often maneuver interleave;The size bigger structure of the beam plank length, the crack run parallel with short side more;Thorough with pierce through sex of temperature crack general and short side direction parallelism or close parallelism, crack along long side cent the segment appear, in the center more airtight.Crack width the size be different, be subjected to temperature variety influence more obvious, winter compare breadth, summer more narrow.The concrete temperature crack that the heat inflation cause is usually in the center the thick both ends be thin, but cold Suo crack of thick thin variety not too obvious.The emergence of the this kind crack will cause the rust eclipse of reinforcing bar, the carbonization of concrete, the anti- jelly which lower concrete melt, anti- tired and anti- Shen ability etc..Main prevention measure:One is as far as possible choose to use low hot or medium hot water mire, like mineral residue cement, powder ash from stove cement...etc..Two is a decrease cement dosage, cement dosage as far as possible the control is in the 450 kg/m 3 following.Three is to lower water ash ratio, water ash of the general concrete ratio control below 0.6.Four is improvement the bone anticipate class to go together with, the Chan add powder ash from stove or efficiently reduce water etc. to come to reduce cement dosage and lower water to turn hot.Five is an improvement concrete of mix blend to process a craft, lower sprinkle of concrete to build temperature.Six is the in addition that the Chan add a have of fixed amount to reduce water and increase Su, slow Ning etc. function in the concrete, improvement the concrete mix to match a thing of mobility,protect water, lower water to turn hot, postpone hot Feng of emergence time.Seven is the heat season sprinkle to build can the adoption take to establish to hide sun plank etc. assistance measure control concrete of Wen Sheng, lower to sprinkle temperature of build the concrete.Eight is the temperature of big physical volume concrete should the dint relate to structure size, concrete structure size more big, temperature should dint more big, so want reasonable arrangement construction work preface, layering, cent the piece sprinkle to build, for the convenience of in spread hot, let up control.Nine is at great inner part constitution of the physical volume concrete cool off piping, cold water perhaps cold air cool off, let up concrete of inside outside difference in temperature.Ten is the supervision which strengthen concrete temperature, adopt to cool off in time, protection measure.11 is to reserve temperature constringency to sew.12 is to let up to control, sprinkle proper before building concrete in the Ji rock and old concrete top build a 5 mm or so sand mat a layer or usage asphalt etc. material Tu2 Shua.13 is to strengthen concrete to protect, the concrete after sprinkle build use moist grass Lian in time, hemp slice's etc. overlay, and attention sprinkle water to protect, appropriate extension protect time, assurance the concrete surface be slow-moving cool off.At the cold season, concrete surface should constitution heat preservation measure, in order to prevent cold wave assault.14 is the allocation be a little amount in the concrete of reinforcing bar perhaps add fiber material concrete of temperature crack control at certain of scope inside.5.Crack and prevention that the chemical reaction causeAlkali bone's anticipating the crack that reaction crack and reinforcing bar rust eclipse cause is the most familiar in the reinforced concrete structure of because of chemical reaction but cause of crack.The concrete blend a future reunion creation some alkalescence ion, these ion with some activity the bone anticipate creation chemical reaction and absorb surroundings environment in of water but the physical volume enlarge, make concrete crisp loose, inflation open crack.In this kind of crack general emergenceconcrete structure usage period, once appear very difficult remediable, so should at under construction adopt valid the measure carry on prevention.Main of prevention measure:While being to choose to anticipate with the alkali activity small freestone bone.Two is the in addition which choose to use low lye mire with low alkali or have no alkali.Three is the Chan which choose to use accommodation with anticipate to repress an alkali bone to anticipate reaction. Because the concrete sprinkle to build, flap Dao bad perhaps is a reinforcing bar protection layer thinner, the harmful material get into concrete to make reinforcing bar creation rust eclipse, the reinforcing bar physical volume of the rust eclipse inflation, cause concrete bulge crack, the crack of this kind type much is a crack lengthways, follow the position of reinforcing bar ually of prevent measure from have:One is assurance reinforcing bar protection the thickness of the layer.Two is a concrete class to go together with to want good.Three is a concrete to sprinkle to note and flap Dao airtight solid.Four is a reinforcing bar surface layer Tu2 Shua antisepsis coating.Crack processingThe emergence of the crack not only would influence structure of whole with just degree, return will cause the rust eclipse of reinforcing bar, acceleration concrete of carbonization, lower durable and anti- of concrete tired, anti- Shen ability.Therefore according to the property of crack and concrete circumstance we want differentiation to treat, in time processing, with assurance building of safety usage.The repair measure of the concrete crack is main to have the following some method:Surface repair method, infuse syrup, the Qian sew method, the structure reinforce a method, concrete displacement method, electricity chemistry protection method and imitate to living from heal method.Surface repair the method be a kind of simple, familiar of repair method, it main be applicable to stability and to structure loading the ability don't have the surface crack of influence and deep enter crack of processing.The processingmeasure that is usually is a surface in crack daubery cement syrup, the wreath oxygen gum mire or at concrete surface Tu2 Shua paint, asphalt etc. antisepsis material, at protection of in the meantime for keeping concrete from continue under the influence of various function to open crack, usually can adoption the surface in crack glue to stick glass fiber cloth etc. measure.1, infuse syrup, the Qian sew methodInfuse a syrup method main the concrete crack been applicable to have influence or have already defend Shen request to the structure whole of repair, it is make use of pressure equipments gum knot the material press into the crack of concrete, gum knot the material harden behind and concrete formation one be whole, thus reinforce of purpose.The in common use gum knot material has the cement the syrup, epoxy, A Ji C Xi sour ester and gather ammonia ester to equalize to learn material.The Qian sew a method is that the crack be a kind of most in common use method in, it usually is follow the crack dig slot, the Qian fill Su in the slot or rigid water material with attain closing crack of purpose.The in common use Su material has PVC gum mire, plastics ointment, the D Ji rubber etc.;In common use rigid water material is the polymer cement sand syrup.2, the structure reinforce a methodWhen the crack influence arrive concrete structure of function, will consideration adopt to reinforce a method to carry on processing to the concrete structure.The structure reinforce medium in common use main have the following a few method:The piece of enlargement concrete structure in every aspect accumulate, outside the Cape department of the Gou piece pack type steel, adoption prepare should the dint method reinforce, glue to stick steel plate to reinforce, increase to establish fulcrum to reinforce and jet the concrete compensation reinforce.3, concrete displacement methodConcrete displacement method is processing severity damage concrete of a kind of valid method, this method be first will damage of the concrete pick and get ridof, then again displacement go into new of concrete or other material.The in common use displacement material have:Common concrete or the cement sand syrup, polymer or change sex polymer concrete or sand syrup.4, the electricity chemistry protection methodThe electricity chemistry antisepsis is to make use of infliction electric field in lie the quality of electricity chemical effect, change concrete or reinforced concrete the environment appearance of the place, the bluntness turn reinforcing bar to attain the purpose of antisepsis.Cathode protection method, chlorine salt's withdrawing a method, alkalescence to recover a method is a chemistry protection method in three kinds of in common use but valid method.The advantage of this kind of method is a protection method under the influence of environment factor smaller, apply reinforcing bar, concrete of long-term antisepsis, since can used for crack structure already can also used for new set up structure.5, imitate to living from legal moreImitate to living from heal the method be a kind of new crack treatment, its mimicry living creature organization secrete a certain material towards suffering wound part auto, but make the wound part heal of function, join some and special composition(such as contain to glue knot of the liquid Xin fiber or capsule) in the concrete of the tradition the composition, at concrete inner part formation the intelligence type imitate to living from heal nerve network system, be the concrete appear crack secrete a parts of liquid Xin fiber can make the crack re- heal.ConclusionThe crack is widespread in the concrete structure existence of a kind of phenomenon, it of emergence not only will lower the anti- Shen of building ability, influence building of usage function, and will cause the rust eclipse of reinforcing bar, the carbonization of concrete, lower the durable of material, influence building of loading ability, so want to carry on to the concrete crackearnest research, differentiation treat, adoption reasonable of the method carry on processing, and at under construction adopt various valid of prevention measure to prevention crack of emergence and development, assurance building and Gou piece safety, stability work.From《CANADIAN JOURNAL OF CIVIL ENGINEERING》建筑施工混凝土裂缝的预防与处理混凝土的裂缝问题是一个普遍存在而又难于解决的工程实际问题，本文对混凝土工程中常见的一些裂缝问题进行了探讨分析，并针对具体情况提出了一些预防、处理措施。

一年级上册数学教案第八单元第五课时解决问题《一共有多少》人教版我今天要为大家带来的是人教版一年级上册数学教案中第八单元第五课时的解决问题《一共有多少》。

一、教学内容我们今天要学习的是第八单元的第五课时，主要内容是通过图片和实际情景，让学生理解并掌握“一共有多少”的概念，学会通过数的加法来解决问题。

二、教学目标通过本节课的学习，我希望学生们能够理解“一共有多少”的含义，学会通过数的加法来求解，并能够应用到实际生活中去。

三、教学难点与重点重点是让学生掌握“一共有多少”的概念和求解方法，难点是能够将所学应用到实际情景中。

四、教具与学具准备我准备了一些图片和实物，用于引发学生的兴趣和理解“一共有多少”的概念。

五、教学过程1. 引入：我先拿出一些图片和实物，让学生观察并提问：“这些图片和实物一共有多少个？”引发学生的思考。

2. 讲解：我通过图片和实物，向学生解释“一共有多少”的概念，并引导学生用数的加法来求解。

3. 练习：我给出一些实际情景，让学生练习计算“一共有多少”，如：“我有3个苹果，你给我再拿2个苹果来，一共有多少个苹果？”六、板书设计我在黑板上写下“一共有多少”的板书，并在旁边画上相应的图片和实物，让学生直观地看到求解的过程。

七、作业设计1. 题目：我有5个橘子，你给我再拿3个橘子来，一共有多少个橘子？答案：5 + 3 = 82. 题目：我有7个铅笔，你给我再拿4个铅笔来，一共有多少个铅笔？答案：7 + 4 = 11八、课后反思及拓展延伸通过本节课的学习，我发现学生们对于“一共有多少”的概念和求解方法已经有了初步的理解和掌握，但在实际应用中还需要加强练习。

下一步，我会通过更多的实际情景和练习，让学生们更好地掌握和应用所学知识。

同时，我也会鼓励学生们在日常生活中，多观察、多思考，将所学知识运用到实际生活中去。

重点和难点解析一、引入环节的图片和实物选择在引入环节，我选择了与学生生活密切相关的图片和实物。

第八单元20以内的进位加法（一）单元教材分析《20以内的进位加法》是20 以内的退位减法和多位数计算的基础，这一部分学习的好坏，将对今后计算的正确率和计算迅速产生直接的影响。

因此，20 以内的进位加法是进一步学习数学必须练好的基本功之一。

（二）单元教学目标1.知道20以内进位加法的基本方法，能熟练、准确地口算20以内的进位加法。

2.学会用加法解决简单的实际问题。

3.通过数学学习，体验数学与日常生活的密切联系，感受数学在日常生活中的作用。

（三）单元重难点教学重点：熟练掌握自己喜欢的口算方法，并能够准确、熟练地算20以内进位加法的口算。

教学难点：理解“凑十法”，并会用“凑十法”计算。

（四）课时安排9课时《9加几》【教学目标】知识与技能：理解“凑十法”，初步掌握9加几的进位加法的思维过程，并能正确计算9加几。

过程与方法：通过问题情境的探索，学生在已有经验的基础上自己得出计算9加几的各种方法，通过比较，学生体验比较简便的计算方法。

情感态度与价值观：培养学生的口头表达能力和初步逻辑思维能力。

【教学重点】理解“凑十法”的算理。

【教学难点】掌握“凑十法”。

【教材分析】9加几的进位加法是学习20以内进位加法的开始，它是在学习了20以内的不进位加法和不退位减法的基础上进行教学的，这节课的教学效果对以后学习8加几、7加几的进位加法……起着很重要的作用。

这部分内容安排了三个层次，一是体现学生解题方法的多样化，突出“凑十法”的计算方法；二是通过“做一做”第1、2题的练习，借助“凑十法”的思维方法，加深对“凑十法”的理解，掌握“凑十法”的计算方法；三是通过“做一做”的第3题，巩固“凑十法”的计算方法。

【教学方法】引导发现，自主观察，合作交流。

【课时安排】1课时【教学过程】一、复习旧知1.口算。

10＋2 4＋10 5＋10 10＋72.看谁算得快。

9+2+1= 5+3+7= 8+4+2=3+2+8= 5+6+5= 7+1+3=二、探究新知1.情境导入校园里正在举办运动会，运动会上的比赛热闹极了,请小朋友们认真的观察一下,同学们都参加了哪些项目？这些运动员参加比赛很辛苦,裁判老师也很辛苦。

第八单元 20以内的进位加法第1课时 9加几一、教学目标1、理解“凑十法”，初步掌握9加几的进位加法的思维过程，并能正确计算9加几的口算。

2、培养学生初步的观察、比较、抽象、概括的能力和动手操作能力，初步提出问题、解决问题的能力，发散学生的思维，培养创新意识。

二、教学重难点重点：会用“凑十法”计算9加几的加法。

难点：理解“凑十法”的思维过程。

三、教学过程：(1)多媒体展示。

(课本第88页的全景图)教师说明：这是学校运动会的场面，从图中你看到了什么?(让学生自己看图互相说一说)教师指出：运动会上，学校为了给运动员解渴，准备了饮料，小红看了看，对其他同学问道：“一共有多少盒?”师：你们知道一共有多少盒吗?互相说一说。

(学生互相说时，教师巡视，注意发现不同的方法)可能出现以下几种情况：数数法。

(1，2，3，4，…，12，13，一共有13盒)接数法。

(箱子里有9盒，然后再接着数10，11，12，13，一共有13盒)凑十法。

(把外面的一盒饮料放在箱子里凑成10盒，10盒再加上剩下的3盒，一共是13盒)师：要算一共有多少盒饮料怎样列式?(板书：9+4)(2)探究9加几的计算方法。

师：9加4该怎样计算呢?请同学们用小棒摆一摆。

①教师指导学生进行操作：左边摆9根小棒代表盒子里的9盒饮料，右边摆4根小棒代表盒子外边的4盒饮料。

教师边引导学生操作边提问：盒子里有9盒，再加上几盒就是10盒?这个l盒是从哪来的?外边的4盒饮料拿走1盒后还剩多少盒?10盒与剩下的3盒合起来是多少盒?所以9+4等于多少?②学生交流计算9+4的方法。

四、教学总结今天我们学习的是9加几，计算9加几的题目，可以用数的方法，也可以用计算的方法。

第2课时 8、7、6加几一、教学目标使学生在实际情境中，正确计算8加几、7加几、6加几；培养学生使用计算方法多样化的能力。

二、教学重难点重点：掌握计算8加几、7加几、6加儿的方法。

难点：培养学生使用多种计算方法的能力。

人教版一年级上册数学教案-第8单元第9课时用数学（2）教学目标：1. 让学生通过观察、操作、交流等活动，进一步理解数的组成，培养学生的观察能力、动手操作能力和口头表达能力。

2. 让学生掌握10以内数的加减法计算方法，并能正确熟练地进行计算。

3. 培养学生运用数学知识解决实际问题的能力，提高学生的数学素养。

教学内容：1. 学习10以内数的加减法计算方法。

2. 解决与10以内数相关的实际问题。

教学重点：1. 10以内数的加减法计算方法。

2. 解决实际问题的能力。

教学难点：1. 理解数的组成，能够灵活运用加减法计算方法。

2. 解决实际问题时，能够将问题转化为数学表达式，并进行正确的计算。

教学准备：1. 教师准备：教学课件、计算器、实物模型等。

2. 学生准备：课本、练习本、铅笔等。

教学过程：一、导入（5分钟）1. 教师通过课件展示一些与10以内数相关的图片，引导学生观察并说出图片中的数。

2. 学生回答后，教师总结并板书10以内数的组成。

二、新课导入（15分钟）1. 教师通过课件展示一些加减法算式，引导学生观察并尝试计算。

2. 教师讲解10以内数的加减法计算方法，并进行板书。

3. 学生跟随教师进行计算练习，巩固计算方法。

三、巩固练习（15分钟）1. 教师通过课件展示一些与10以内数相关的实际问题，引导学生运用加减法计算方法进行解决。

2. 学生独立完成练习，教师巡回指导。

四、课堂小结（5分钟）1. 教师引导学生回顾本节课所学内容，总结10以内数的加减法计算方法和解决实际问题的方法。

2. 学生分享自己的学习心得，教师给予鼓励和指导。

五、课后作业（5分钟）1. 教师布置一些与10以内数相关的练习题，要求学生课后完成。

2. 学生认真完成作业，家长签字确认。

教学反思：本节课通过观察、操作、交流等活动，让学生进一步理解了10以内数的组成，掌握了加减法计算方法，并能正确熟练地进行计算。

同时，通过解决实际问题，培养了学生运用数学知识解决实际问题的能力。