上海版牛津初中英语课件Chapter 4 Reading 3.ppt

chapter 4 reading 3 p49,calculating machines,what are the three calculating machines? why do people still use abacuses? what is an abacus made up of? what do the beads mean on the abacus? what can an electronic calculator do? what do you think of computers as calculating machines? give an example.,because they are so fast and accurate.,beads and wires.,they represent ones, tens hundreds and thousands, starting fron the bottom wire.,it can add, subtract, multiply, divide and calculate percentages and square roots.,very powerful.,an abacus, an electronic calculator and a computer.,read & answer,one of the first calculating machines was an abacus. abacuses are so fast and accurate that people still use them today. on the abacus in the picture, the beads on the wires represent ones, tens, hundreds and thousands, starting from the bottom wire.,_,_,_,_,_,_,_,_,_,the picture on the right shows a modern electronic calculator. it can add, subtract, multiply and divide. it can also calculate percentages and square roots.,_,_,_,_ _ _,_,_,_ _,this picture shows a computer. computers are very powerful calculating machines. in a flash, a computer can do a calculation that you could not do in your whole lifetime.,_,_,_,_,_,x23 =,916748676920039158098660927585380162483106680144308622407126516427934657040867096593279205767480806790022783016354924852380335745316935111903596577547340075681688305620821016129132845546805780158806771,x =,who can solve the problem?,shakuntala devi,an indian lady,_,brain against computer,a human brain,which is more powerful?,brain against computer,what do we call the brain? what brain does shakuntala have? how fast can she calculate? how long did it take her to find the answer? how long didit take the computer to do it? what did people to to the computer before it began calculating? did anyone program shakuntala? is a human brain a more powerful calculator?,a living computer.,an amazing brain.,like lightning.,fifty seconds.,a mimute.,people had to program it with instructions.,no.,yes.,listen, read & answer,ancient numbers in tens ./ ancient people wrote numbers in different ways, but counted them in the same way - in tens. indians invented and developed the system of numbers from 1 to 9 and 0. something about three calculating machines. a human brain is more powerful than a computer.,.,.,.,.,main ideas for each part,brain against computer some people called brain a living computer. is a human brain a more powerful calculator than a computer? the following story may give an answer. shakuntala is a lady from india with an amazing brain. she can calculate like lightning. in america, shakuntala and a computer were given this problem to solve.,_,_,_,_,_,_,_,_,_,_,_,_,_,shakuntalas brain took fifty seconds to find the answer.the computer took a minute. however, before the computer could begin calculating, someone had to program it with instructions, and that took many hours. no one had to program shakuntala! use your own living computer to solve the problem above, if it is not power