Help me write a review of Ma Chaohu's "Water"

Excerpts and comments from the "Water" classroom record

1. Observe what water is like

Teacher: What is water? Let’s study it together today. (Write on the blackboard: water) There is a sink on the table, two cups, and a clean chopstick for each person. You can play however you want, discover what water is like from playing, and see who can explain it most comprehensively after a while.

Comment: The meaning of material structure is clear. But some places can still be studied, which will be mentioned later.

(Students play in the water. The teacher visits each group and occasionally talks to the students. The duration is 5 minutes.)

Teacher: Everyone has a great time. Now let’s talk about water. What.

(After watching the teaching video, Teacher Liu Mogeng thought it was better to say "try" instead of "play", and to train students to observe carefully and carefully, not "play".)

Health: Water is tasteless and white.

(The teacher briefly recorded the students’ speech on the blackboard: tasteless, white. From now on, each student’s speech will be briefly written on the blackboard.)

Student: Fill the cup When water is added, the cup sinks; when water is not filled, the cup floats. The small cup is filled with water and poured into the big cup. The big cup is not full.

Comment: Here, the object of student research is no longer water, but the volume of the cup. The cup that students are familiar with is the cup as a container. If the teacher does not provide guidance during the inspection, the student's research object may be changed at will. If these two cups are intended to allow students to conclude that water is an object with no fixed shape, thereby providing a representation for establishing the concept of "liquid", then the shapes of the two cups selected can be more different, for example, one is round and the other is square. of. But attention should be paid to guiding students to observe the water, not the cup itself, that is, observe the shape of the water in the cup or the shape of the water when pressed in the sink to drain it, etc.

Teacher: Do you mean that there are two meanings? The first meaning is that the water in the small cup cannot fill the big cup. How should you write it? (Students agree to write it as not filling the large cup.)

Sheng: Stir the water with a stick, and the water will bubble. Stir the water with your hands, and the water will bubble.

Sheng: I can’t hold it in the water, and it will fall down as soon as I catch it.

(The teacher asked this student to come to the podium and show everyone how he caught the performance. The student put one hand into the water to catch it. As soon as the hand left the water, the water in his hand went to Drops. The teacher grabs the water with both hands)

Teacher: What should I say in this situation? How should I write it?

Student: The water fell and flowed into the sink again.

Teacher: Is it okay to write "water will flow"? Comment: It can be seen that the teacher regards the method of allowing students to establish "liquid" as the focus and difficulty of teaching this lesson. Therefore, students are repeatedly guided to perceive and experience here, and this will be the case in several subsequent places. This is the biggest feature of this class.

(Students agree)

Student: I saw that the chopsticks in the water were bent.

Teacher: You mean two things: one is that the chopsticks placed in the water look bent; the other is that the chopsticks in the water can be seen when the chopsticks are placed in the water. What to say in this situation?

Sheng: Water is transparent.

Student: A thing is placed in the water and can be seen outside.

(The teacher placed a chopstick on the back of the sink and asked the students to look at the chopsticks through the water-filled sink from the other side. The students said they could see it.)

Student: This It's called transparency.

Study: Water is placed in a vat, and the water in the vat also sways.

Teacher: What he said about shaking is somewhat similar to what was written on the blackboard?

Sheng: It’s the same as bubbles.

Sheng: It’s the same as water flowing down.

Sheng: If you shake it hard, the water will flow out.

Comment: It seems that the teacher is a bit impatient. In fact, there is no need to classify at this time. At this time, students should be allowed to perceive the research object from all aspects and express the results of perception accurately and carefully. This is the basis for achieving the teaching purpose of this lesson, so students should be allowed to speak fully.

After that, several students said valuable phenomena: "It's the same as water flowing down", "If you shake it hard, water will flow out", and some students put their fingers Insert it into the water and pull it out, etc. Unfortunately, the students were not allowed to fully explain it.

In fact, the more complete the accumulated representations that students perceive, the easier it is to form concepts. Teacher: Just now a classmate did this action (sniffing), what does it mean?

Comment: Enlightenment at this time is necessary. "Water has no smell" is not a very obvious feature, and students can easily ignore it. These are places where teachers need to take the lead.

Raw: The water does not smell fragrant or sweet.

Sheng: The water is light.

raw: water has no taste, no fragrance and no sweetness.

Comment: Please pay attention to the students’ way of expression. This issue will be covered later.

Teacher: Who can tell me what water smells like?

Health: Water smells.

Sheng: The smell is low.

Teacher: Is there any aroma or smell?

Sheng: No.

Teacher: The water is light and has no smell.

(The students’ speeches are recorded on the blackboard as follows: Water has no taste and is white in color. If it is not filled with cold bubbling water, it will run clear and have no smell)

2. Organize the perception of water< /p>

Teacher: Look at what’s written on the blackboard. Do you have any opinions?

Sheng: Water has no color at all.

Comment: This is a good question. Maybe the teacher just wants to adjust the students' language, but actually helps the students deepen their thinking. The former student said: "Water has no color." The latter student said: "Water has no color." It seems that the content is the same, but it expresses two levels of thinking. The former does not break away from specific reference objects. His thinking process is: water is not red, nor green, nor purple... Therefore, he can only draw the conclusion: "it is not any color". . After the teacher asked the question, the student's thinking process changed, and the specific characteristics of red, green, purple... were discarded and abstracted into the concept of "color" without the support of specific things. The higher the abstraction of a concept, the wider its scope of application. These key points must be grasped in teaching. Whether these areas are grasped to develop students' thinking level is the key to the teaching effect and an important sign of teacher maturity.

Teacher: How to say "It's not any color"?

Student: Water has no color.

(The teacher erased the word "white" in "white color" and changed it to "no".)

Teacher: "It can't be filled". Water can be poured from a small cup into a large cup. , which classmate is talking about the same thing?

Teacher: Turn it upside down, turn it upside down, and the water will flow. (The teacher wiped off the words "not full" and "bubbles" on the blackboard.)

Comment: These areas were handled a little rough. What the teacher writes on the blackboard are all phenomena observed by the students and are objective facts. It is best to explain every fact. These facts can be roughly divided into three categories: One category has nothing to do with the characteristics of water. For example, "not full" actually compares the size of two containers; one type is related to the characteristics of water and needs to be expressed in concepts, such as "water has no color"; and the other type is also related to the characteristics of water, But it is not yet possible to express it in terms of concepts, but it contains quite rich research content. For example, "bubbles" not only reflects that air is not easily dissolved by water, but also reflects that water has surface tension and is also reflected by water. The air trapped inside is less dense than water. Another example is "The chopsticks are bent" reflects the different refractive index of water and air. These phenomena can tell students the characteristics of water, but if you don’t study them now, you can study them later. Don’t simply wipe them away. This may reflect the tendency of teachers to only focus on drawing specific conclusions and neglect traditional teaching ideas of cultivating interests and abilities to a certain extent.

Teacher: You said that water is tasteless, colorless, cold, and transparent. If there is a person who has never seen water and hears you say water, will he think of this ( The teacher shows a piece of glass) and thinks it is water. It is also tasteless, colorless, cold and transparent. How do you tell him?

Comments: This design is very good. It starts from helping students establish the concept of "liquid" and creates a little contradiction to stimulate students' thinking on the basis of students' richer representations. From the practical effect, it deepens students' understanding of "liquid".

Sheng: That’s glass.

Sheng: I don’t think glass is water.

Teacher: Why?

Sheng: Because water is soft.

Sheng: Water will flow, but it will not flow.

Sheng: Glass is hard.

Teacher: (The teacher poured white pebbles from one cup into another cup) Does this flow?

Sheng: No.

Sheng: Because the stone will ring when it falls.

Sheng: It has color.

Sheng: Water is not like this. The water flows down together, not one by one.

Student: If you touch the water with your hands, your hands will be wet.

Teacher: What about glass?

Sheng: It is hard.

Student: Very hard.

Teacher: Where is the water?

Sheng: Very soft.

Teacher: Now I pour the rocks on the table. What do you think happens?

Study: If a stone is poured on the table, it will not flow, but if water is poured on the table, it will flow.

Sheng: It is piled together.

Student: If they are squeezed together in a cup, they will become loose when poured on the table (meaning "spread out")

Teacher: Water will flow, but stones will not. We call flowing things like water liquids ("liquid" written on the blackboard).

Teacher: Glass is also cold. (The students agreed to remove the word "cold")

Who can give a comprehensive explanation now: What kind of thing is water?

Student: (Speaking to the writing on the blackboard) Water is tasteless, colorless, odorless, liquid, and transparent.

Teacher: Very well said. Let’s organize the records on the blackboard again to make it easier to talk about. (The teacher moves the word "liquid" to the back of "transparent" and asks a student to say it once, and everyone says it together.)

Overall comments: The purpose of this lesson is to understand what water is like objects, and in this understanding process, students' observation, comparison and analysis abilities are further developed. This 20-minute classroom record is the main part of this class and basically reflects the actual situation of this class.

The most successful aspect of this class is that it allows students to fully understand the research object. Through observation and hands-on operations, students discovered a wealth of facts, accumulated representations, and then formed concepts about the characteristics of water on this basis. It can be seen that these conclusions are not forced on students by teachers, but abstracted and summarized by students themselves from personal observation of natural phenomena. At this point, this lesson reflects the main results that the nature teaching reform has achieved.

This lesson also does a good job in guiding students to analyze materials and organize materials to form concepts. Especially in the process of helping students establish the concept of "liquid", it not only mobilizes students to research problems The enthusiasm of teachers also plays a better role. However, it also reflects a common problem in current nature teaching: teachers are eager to draw specific conclusions, which affects students' full development of thinking. In this course, it is mainly manifested in these aspects.

First, if teachers think that the materials that students obtain through perception are not directly related to the specific conclusions of the lesson, they will often deal with them relatively simply. Teachers may want to lead students on a smooth sailing path to the conclusion, thereby losing an excellent opportunity to develop students' interests and abilities.

The second is that teachers are eager to make simple affirmative or negative judgments on questions related to specific conclusions during student discussions, which makes students focus their main energy on finding answers that are satisfactory to the teacher, and it is difficult to be active and proactive research issues. We cannot seriously absorb information from classmates and draw our own conclusions based on the facts we have obtained.

Teacher: Xu Wen, Wuchang Baoan Street Primary School, Wuhan

Comment: Canghai