Unit 2 What’s the matter with Daming ?

Teaching goals:

知识与技能：通过图片、任务认领等环节，全部学生能初步学会运用What’s the matter with you?及其答句I lost my?通过知识拓展、交流，90%以上的学生能熟练运用What’s the matter with?提问并根据具体情况用适用的第三人称单数来回答。 过程与方法：通过听、跟读、自读等多种形式，使学生能正确理解课文内容， 初步培养学生用英语思考和交流的习惯及在情境中灵活运用所学句型的能力和知识迁移能力。

情感态度与价值观：学生通过合作学习能够形成一定的团队精神，同时通过课文的学习能够获得关心他人、帮助他人以及拾金不昧的教育。

Importances and difficuities：

1、能在适当的语境中用What’s the matter with?句型及其答句。

2、能结合所学的语言知识，通过联系生活实际，灵活运用What’s the matter with?及其 答句，特别是第三人称形式。

Teaching steps：

Step 1 Warm-up

1、Greetings and free talk:

Hello, everyone!

How are you?

Did you go to school by school bus?

What did you take? A bag or a kite?

Did you take your yellow cap?

Did you buy shoes yesterday?

2、Let’s play a game : I say and you do.

Point to your head; Point to my desk. Point to his hand.Point to her nose.Point to his book.Point to her bag.

Step 2 Lead in

You did a good job. Now please take out your English book. （拿出你的英语书，放到桌面。）

T：What’s the matter?

S: My English book is lost. （书不见了）

You can say: I lost my English book. (板书 lost lose 简单介绍含义，与四年级学过的lost迷路的意思相区分)

Step 3Presentation

(一)Part 1

1、What’s the matter with Ben? Let’s watch the video and find out the answer

(进入到第一部分的文本，跟读一遍，然后回答问题)

What’s the matter with you, Ben? A. I lost my book. B. I lost my cap. Did Ben find （找到）his cap?

Did Lili help Ben?

Yes, we should help the others.

2、检测评价： 课件呈现不同孩子及物品，集体操练句型。

3、小组合作，藏起同桌的某一物品，询问：What’sthe matter with you, xxx ? 回答：I lost my ?

(二)Part 2

We know Ben lost his cap and he found it , But Damingisn’t happy. What’s the matter with Daming?（板书课题）Please watch the video and answer these questions:

1、What’s the matter with Daming? A He lost her bag. B. He lost his bag.

2、What was in his bag? A.皮鞋 B.运动鞋。

3、Where were his sports shoes? A. In the bag. B. On the school bus

4、Where was his bag? A.校车 B.公交车

Let’s watch the video and choose the correct answer.

First let’s look at picture 1 . Read after the tape and try to answer Step 4 Questions

1、 What’s the matter with Daming? A He lost her bag. B. He lost his bag.

Yes, he lost his bag. Because Daming is a boy ,so we can’t say “he lost her bag.”

Look, Can you ask and answer?

Well done. Let’s go on.

2、Please read Picture 2 and choose the correct picture.

What was in his bag? A. 图片呈现皮鞋 B.图片呈现运动鞋。

Guess: What are sports shoes?

I think you did a good job.

3、 Did Daming find his bag and his sports shoes? Let’s watch the video and try to find the answer.

Where were his sports shoes? A. In the bag. B. On the school bus Where was his bag? A. 图片呈现校车 B. 图片呈现公交车

Did Daming find his bag and his sports shoes?

Step 5 Practice

Let’s play a game

小游戏：抽单词卡片，然后表演完整对话，操练句型。

T:What’s the matter with you,××?

S1: I lost my....

T:What’s the matter with ××?

S2:He/She lost his/her...

Step 6Sum and test

Can you tell me what you have learned in this class? Can you do ?检测题（每人一张纸，练习书写）

What’s the matter with Daming? He lost his _____.

What’s the matter with Amy? She lost ________ _____.

___________________ Sam? He lost ________________.

_______________________? She __________________.

Blackboard design：

What’s the matter with Daming ?

He lost his ...

教学反思：

第二篇：Mesure the Resistance via the Wheastone Bridge 电桥法测电阻 实验报告 英语

Measure the Resistance via the Wheastone Bridge

1.The purpose:

i.              To understand the principle and characteristics of the Wheatstone bridge.

ii.              To understand the concept of sensitivity of bridge.

iii.              Learn the “exchange measure method”, with which to eliminate the system error.

2.The apparatus:

   Unknown resistances; DC power supply; galvanometer; resistor box; variable resistor; switch and other electrical components; electrical bridge.

3.Theories:                                                    

1)The principle and the structure of the Wheatstone bridge

 

When U_C=U_D

R_X=

2)The sensitivity of the Wheatstone bridge

Because of the sensitivity of the galvanometer is limited, the current through the galvanometer is not truly zero, and the galvanometer cannot efficiently measure it.

The sensitivity of the bridge is defined as the ratio between the deflection of the galvanometer, Dd, and the corresponding relative value of R₀.

S=

3)The “exchange measure method”.

Exchange the positions of R1 and R2, or R0 and Rx, and adjusting R0 to R0 ¢, the bridge can get a new balanced state，and               R_X= 

Combine this equation with R_X=, we can get:

R_X=

This equation has nothing to do with R₁ and R₂. In this way we can make the error only relate to the instrument error of R₀, which is the instrument error of resistor box.

4.The procedures:

1)     Use simply constructed bridge to measure the metal film resistor.

Connect the circuit and measure the resistance then exchange R₀ and R_X measure the resistance again.

The key points:

         i.              Find the balance point.

       ii.              Measure the sensitivity of the bridge.

    iii.              Exchange R₀ and R_X measure the resistance again.

Error analysis:

The uncertainty of R₀:

_apparatus=R_{0 apparatus}=0.1%R_o+0.005(K+1)

The error caused by the sensitivity of the bridge is:

Δ=R₀  (S is the sensitivity of the galvanometer)

U_Ro=

The relative uncertainty of R_X is:

= (N=1.0)

2)     Use box-bridge to measure the resistance.

         i.              Make the reading of galvanometer back to “0” via mechanical method.

       ii.              Open K, press G button, adjust M and keep the galvanometer balance.

    iii.              Connect R_X with X.

     iv.              Adjust the system and record the resistance R₀ which make the galvanometer balance.

Error analysis:

The limit of fundamental error is:

E_lim=α%(NR_o+)

The error caused by the sensitivity of the bridge box is:

Δ=NR₀

The relative uncertainty of R_X is:

U_Rx=

5.Data processing:

TEST ONE.

Use simply constructed bridge to measure the metal film resistor.

a)      For U=8V R_inner=100Ω

R_X==Ω=498.35Ω

S===277

The uncertainty of R₀:

_apparatus=R_{0 apparatus}=0.1%R_o+0.005(K+1)

=0.1%497.7Ω+0.005(4+1)=0.5227Ω

The error caused by the sensitivity of the bridge is:

Δ=R₀=497.7Ω=0.3594Ω

U_Ro=

==0.63434Ω

The relative uncertainty of R_X is:

=

==9.0123x10^-4

==9.0123x10^-4x498.35Ω=0.45Ω

R_X=498.350.45Ω

b)      For U=8V R_inner=2500Ω

R_X==Ω=499.05Ω

S===53.6

The uncertainty of R₀:

_apparatus=R_{0 apparatus}=0.1%R_o+0.005(K+1)

=0.1%498.1Ω+0.005(4+1)=0.5231Ω

The error caused by the sensitivity of the bridge is:

Δ=R₀=498.1Ω=1.859Ω

U_Ro=

==1.9312Ω

The relative uncertainty of R_X is:

=

==2.7415x10^-3

==2.7415x10^-3x499.05Ω=1.4Ω

R_X=499.01.4Ω

c)       For U=4V R_inner=100Ω

R_X==Ω=498.85Ω

S===135

The uncertainty of R₀:

_apparatus=R_{0 apparatus}=0.1%R_o+0.005(K+1)

=0.1%497.7Ω+0.005(4+1)=0.5227Ω

The error caused by the sensitivity of the bridge is:

Δ=R₀=497.7Ω=0.7373Ω

U_Ro=

==0.90378Ω

The relative uncertainty of R_X is:

=

==1.2840x10^-3

==1.2840x10^-3x498.85Ω=0.6Ω

R_X=498.80.6Ω

d)      For U=4V R_inner=2500Ω

R_X==Ω=499.15Ω

S===31.1

The uncertainty of R₀:

_apparatus=R_{0 apparatus}=0.1%R_o+0.005(K+1)

=0.1%498.2Ω+0.005(4+1)=0.5232Ω

The error caused by the sensitivity of the bridge is:

Δ=R₀=498.2Ω=3.010Ω

U_Ro=

==3.0551Ω

The relative uncertainty of R_X is:

=

==4.3362x10^-3

==4.3362x10^-3x499.15Ω=2.2Ω

R_X=499.22.2Ω

TEST TWO

Use box-bridge to measure the resistance.

A.      For resistor R_X1

S===17.4x10³

The limit of fundamental error is:

E_lim=α%(NR_o+)=0.1%x5120.4Ω+1Ω=6.1204Ω

The error caused by the sensitivity of the bridge box is:

Δ=NR₀=1x5120.4Ωx=0.058855Ω

The relative uncertainty of R_X is:

U_Rx==

   =6Ω

R_X=51206Ω

B.      For resistor R_X2

S===26.9x10³

The limit of fundamental error is:

E_lim=α%(NR_o+)=0.1%x10^-1x4983.8Ω+0.1Ω

=0.59838Ω (=10000, and I get it from

E_lim=α%(NR_o+)=₀+1)

The error caused by the sensitivity of the bridge box is:

Δ=NR₀=10^-1x4983.8Ωx=0.0037054Ω

The relative uncertainty of R_X is:

U_Rx=

=

   =0.6

R_X=498.46Ω

Discussion:

In the 1^st test, “use simply constructed bridge to measure the metal film resistor”. As we can see that the “exchange measure method” eliminated the error which caused by the uncertainty of R₁ and R₂.Thus the main error in this experiment is the instrumental error of the resistor box (U_Ro). The instrumental error is mainly caused byR_{0 apparatus}. The error caused by the sensitivity of the bridge (Δ) also contributes to the error U_Ro.

   From the form, we can get that R_{0 apparatus} plays an important role in the error when the inner resistance of the galvanometer is relative small or the voltage of the power is relative larger. On the other hand, the error caused by the sensitivity of the bridge (Δ) is the main error when the inner resistance of the galvanometer is big or the voltage of the power is small.

In the 2^nd test, “use box-bridge to measure the resistance”.

The main error is the fundamental error limit (E_lim) and the error caused by the sensitivity of the bridge box (Δ).

   We can easily get that the main error in “use box-bridge to measure the resistance” is the fundamental error limit (E_lim). And the error caused by the sensitivity of the bridge box (Δ) is so small that it can be neglected.

6.Conclusions:

From this experiment we can get that:

In the 1^st test, “use simply constructed bridge to measure the metal film resistor”

In the 2^nd test, “use box-bridge to measure the resistance”.

What’s more, when we use simply constructed bridge to measure the resistance, we’d better use a power supply with relative high voltage and also we should use a galvanometer with small inner resistance.

   While we use the box bridge, the error mainly relate to E_lim, and E_lim=α%(NR_o+), thus it is better to measure small resistor with box bridge.