人教版2020年八年级英语上册section a (gf-3c) 教学课件33

I read English books about twice a week.
The Adverbs of Frequency
Lead in
Make conversations with your partner. How often do you do these activities?
help with housework every day
sometimes 有时 40﹪ at times, now and then
hardly ever 几乎不 20﹪ almost not, not at all
never 从不 0﹪ not ever, not at any time
针对上面所说的频度副词和表示“在某段时 间内某种动作的次数”的状语提问时，都要用 how often。
C 3. —Would you like some coffee? —No, thanks. I ______ drink coffee. Coffee is bad for my stomach. A. usually B. often C. hardly D. always
3a Complete the questions with do or does. Then match the questions and answers.
once a week
twice a three week times a
week
write English letters?
see English movies?
have English parties? have English lectures?
Summary
Summary
1．Key vocabulary：maybe，at least， once a month，stay up，twice a
A: How often do you use the Internet? B: Once a week.
How often does he / she …?
频度副词
频度副词 词 义 频 率 英 文 释 义 always 总是 100﹪ all the time usually 通常 80﹪ often, generally often 经常 60﹪ ( at ) many times
声音的传播靠固体、液体、气体等 介质，电磁波的传播需要介质吗？
把一个移动电话放在真空 罩中，并给这个移动电话打电话。 这个移动电话能够收到此信号吗？
由实验可以看到，放在真 空罩中的移动电话可以收到罩 外传给它的电磁波。这说明电 磁波在真空中可以传播。
• Practice the conversation using the sentences in Grammar Focus.
教学目标
1.知识与技能 （1）了解电磁波的产生和传播； （2）知道光是电磁波，电磁波在真空中的 传播速度； （3）知道波长、频率和波速的关系。
教学目标
2.过程与方法 （1）通过演示了解电磁波的存在，电磁波在 真空中的传播； （2）通过观察图表，认识电磁波在不同波段 有不同的作用。 3.情感态度与价值观
sing English songs speak English with foreigners
join the English corner do some English exercises
Interview
How often do you …? • read English books • sing English songs • watch English programs • listen to English tapes • join the English corner • chat with foreigner
apples? 6. __D__o__ your parents play
sports?
a. Yes. She usually does. b. Hardly ever. I don’t
like them. c. He plays at least
twice a week. d. No, they don’t.
木棍在水面上振动 会产生水波；说话时声带 的振动在空气中形成声波。 与水波、声波的形成相似， 导线中电流的迅速变化会 在空间激起（产生）电磁 波。
广播电台、电视台 以及移动电话靠复杂的电 子线路来产生迅速变化的 电流，发出电磁波。电磁 波有许多用途，比如，可 以用来传递信息。
移动基站靠 电磁波传递信息。
How often do you… Names
Frequency
Read English books? Lin Ying twice a week
Group Work
What can you do to improve your English?
read some English books watch English program
八年级（上）
Unit 2
How often do you exercise?
Section A (GF-3c)
学习目标
Key words & phrases:
maybe，least，at least，once a month，stay up， twice a week，eat a healthy breakfast，go to bed， play sports，after school
A: How often do you read the English book? B: I like reading. I read English books about twice a week.
How often do you …?
read English books? sing English songs?
Questions 1. ___________?(how often / help with housework) 2. ___________?(what / usually / do / weekends) 3. ___________?(how often / best friend / exercise) 4. ___________?(what / usually / do / after school)
My partner’s answers
_____________
_____________
_____________
_____________
Discussion
Discuss with your partners your daily activities. How often do you do them? Why do you like them? e.g. A: What do you usually do at weekends?
换句话说，如果要回答由how often提问的句 子，我们通常要用频度副词或诸如every day,
each week, once a week, twice a day, four times a month等来回答。
单项选择 C1.What ______ she usually ______ on Sunday?
Key sentences:
1.What do you usually do on weekends？ I always exercise.
2. Do you go shopping？No，I never go shopping. 3. How often do you read English books？
电磁波在信息的传 递中扮演着非常重要的 角色，所以，要研究信 息的传递，就要研究电 磁波。
尽管你对电磁波这 个名词已经十分熟悉， 但是，你知道电磁波是 怎样产生的吗？
打开收音机的开关，旋至 没有电台的位置，将音量开大。 取一节干电池和一根导线，拿 到收音机附近。先将导线的一 端与电池的负极相连，再将导 线的另一端与正极摩擦，使它 们时断时续地接触。从收音机 里听到什么？
1. How often __d_o_e_s_ he play soccer?
2. __D__o__ you drink milk? 3. How often ___d_o__ they
stay up late? 4. _D__o_e_s_ Sue eat a healthy
breakfast? 5. How often ___d_o__ you eat
They’re too busy. e. Never. They always
go to bed early. f. Yes, I do. Every day.
3b Use the words given to write questions. Then
ask and answer them with a partner.
在一系列水波的传播过程中，凸起 的最高处，叫做波峰；凹下最低处，叫 做波谷。相邻的两个波峰（或波谷）的 距离叫做波长。
在某个确定位置，1s内有多少次波峰 或波谷通过，波的频率就是多少。水波不 停地向远处传播，用来描述波的传播快慢 的物理量叫做波速。
跟水波类似，电磁波也有自己的频 率、波长和波速。
B: I like going shopping. A: How often do you go shopping? B: Twice a month. A: Why do you like it? B: It’s exciting.
Discussion
Discuss with your partners your daily activities. How often do you do them? Why do you like them? e.g. A: What do you usually do at weekends?