1、2+5 =?,Whats two plus five?,Its seven.,7,+,3+6 =?,Whats three plus six?,Its nine.,9,+,1+4,3+6,2+5,one plus four,two plus five,three plus six,Practice: A: Whats plus? B: Its ,A:Whats five plus two? 5 + 2 = ?,B:Its seven.,?,A: Thats right.,7,十,Questions:,?,A: Whats eight plus five? 8 +5 =?,B: Its thir
2、teen.,A: Thats right.,13,Questions:,Whats ten plus four? 10 + 4 = ?,Its fourteen.,?,Thats right.,14,十,Questions:,5,4,3,2,1,15,16,17,18,19,Whatsplus? Its twenty.(20),Questions:,fifteen,sixteen,seventeen,eighteen,nineteen,13thirteen,14fourteen,15fifteen,16sixteen,17seventeen,18eighteen,19nineteen,20tw
3、enty,12twelve,Whats missing？,Whats nine minus four ?,Its five,9-4=?,Whats eight minus two?,Its six.,8-2,20-10=?,A: Whats twenty minus ten？,B: Its ten.,90-40,80-20,50-40,ninety minus forty,eighty minus twenty,fifty minus forty,11-6=,9-4=,7-2=,12-8=,10-1=,14-7=,6-4=,13-5=,8,9,7,4,5,2,Questions:,1,2,7,6,3,4,5,A: Whats plus /minus? B: ItsA: Thats right. Sorry, youre wrong. Oh, no.,Make a conversation,设计一份加减法口算试卷,与周围同学一起练习英语表述.朗读并背诵Lesson 21。,Homework,Thank youGoodbye,练习二,思考题：,下图表示用棱长1厘米的正方体摆成的物体。,（1）从前面、上面和右面看到的分别是什么形状？试着画一画。,（2）这个物体的表面积是多少平方厘米？,（3）如果添加同样的正方体，把这个物体补成一个大正方体，表面积至少是多少平方厘米？,
