Scientific concept:

1, the changes of substances can be divided into two categories: physical changes and chemical changes, and their difference is that no new substances are produced.

2. In the process of change, some substances will change both chemically and physically.

Process and method:

Learn to separate the mixture with a sieve and heat the sugar with a candle.

Emotions, attitudes and values:

1, form the habit of careful observation and timely recording.

2. In the process of experimental operation, it is very important to report the observed phenomena seriously and truly for drawing correct conclusions.

Teaching preparation

Each group has a cup of sand, a cup of soybeans, a candle, a piece of white paper, a spoon, a small packet of sugar and a sieve.

(3) Teaching process

First, review the introduction.

Teacher: Through the last lesson, we already know what the world is made of. (substance)

Matter is always changing. In this lesson, we carefully study what has happened to matter through experiments. Blackboard: What happened to matter?

Second, observe the changes of matter.

Show me some sand and beans.

1, Teacher: I only give you sand and beans. Under what circumstances may they change? (Health: Mixed)

Teacher: How do we know if they have changed? (Health: Compare the mixed sand and beans with those before mixing)

Teacher: So can you mix sand and beans? (Health: No, we need to keep some)

Teacher: Then let's pour some sand and beans on white paper before mixing, and observe and record their respective characteristics, shall we?

Teacher: Let's mix the sand and beans in the cup and see if the sand and beans will change. What is your guess?

Teacher: Is there any way to see more clearly? (Observe separately with a sieve)

2, teacher evaluation, learning "record form"

(2) show candles and sugar.

1, Teacher: Under what circumstances may candles and sugar change? (Sanitation: heating)

2. Teacher: Can you learn from the previous observation methods and talk about how to observe the changes of sugar when it is heated?

(Health: First observe the characteristics of sugar, then predict the change of sugar heating, then heat sugar, and observe the change of sugar during and after heating. )

3. Teacher: It is dangerous to heat sugar. Here the teacher will give you a hint (show the "friendly hint" for the students to see).

4. Teacher: Don't forget to record the experimental operation (show the "record sheet").

(3) experimental operation, observation of material changes.

1, get the experimental data, and experiment in groups (in turn).

2. Observe the changes before and after the substance, and make records.

Activity 1: Record the mixed change table of sand and beans.

Year, month and day group recorder

Before mixing

predict

Changes after mixing

sand

peas

Activity 2: Heating Sugar Change Record Sheet

Year, month and day group recorder

Before heating

predict

Change after heating

refined sugar

(4) Feedback experimental records and exchange discussions.

1. Is there any obvious difference between mixing sand and beans and heating sugar? The mixing of sand and beans has no obvious change, but the heating of sugar has obvious change. )

2. Is the black thing left after the sugar is fully heated still the original sugar? What does this mean? (Explain that white sugar produces new substances during heating. ) blackboard writing: produce new substances.

However, there is no obvious change after sand and beans are mixed. What do you mean by sand or sand, beans or beans? It shows that the mixing of sand and beans will not produce new substances. ) blackboard writing: no new substances are produced.

3. Judgment: Look at the picture and tell me whether these changes have produced new substances. What changes have happened to them?

Third, summarize the characteristics of physical and chemical changes.

1, Teacher: Some changes only change the shape, volume, state and so on. Matter does not produce new matter different from the original. We call this change physical change. Such as: sand and beans mixed.

Some changes produce new substances, and we call changes with new substances chemical changes. Such as heating sugar.

In fact, some substances in the heated sugar have changed. Have you noticed? (Students, for example, tell us what has changed? Why? )

Show extracurricular materials to read:

The candle is burning, the flame is dancing, and the candle is getting shorter. What new substance does the candle become after burning? Where did these new substances go? We only see that candles are decreasing, but we don't see new substances. Will matter decrease or disappear? In fact, a completely burned candle will produce water and carbon dioxide. The hydrogen and oxygen in the candle will form water, and the water will be converted into steam, which will spread into the air due to high temperature. Since water vapor and carbon dioxide are colorless, they are invisible. If the candle is not burned sufficiently, it will also produce some carbon components. You can take an iron product and sweep it on the candle flame, which will leave traces of carbon black.

Can you name other physical changes around us? What material changes are chemical changes?

Fourth, the curriculum is extended and deepened.

1, Discussion: Is there any physical change during the chemical change of white sugar heating? Is there any physical change in the chemical change of candle burning?

(1) What's the difference between solid white sugar changing into liquid sugar and white sugar changing into black charcoal?

(2) What is the difference between changing candles into candle oil and burning candle oil into gas?

2. Conclusion: In the process of change, some substances will change both chemically and physically. It can also be said that chemical changes are often accompanied by physical changes. Do you believe it or not? Do you want to go home and continue exploring?

3. What have you gained from this course?

Blackboard design: What happened to matter?

Change shape

Changing the size will not produce new physical changes.

Change state

……

Changing color will produce new chemical changes in matter.

Give off a dim light

……

Constructing scientific concepts in long-term exploration

-Reflect on what happened after class

The report class of the training class for rural science backbone teachers has been notified for a long time. I didn't expect this semester to be so early, and the theme was also determined as "long-term exploration". After some consideration, I decided on the content: Book 6, Grade 6, Lesson 2, Unit 2: What happened to something important? Two inquiry activities are arranged in the textbook: one is to mix sand and beans, so that students can know through observation and inquiry that there is no new substance different from the original, that is, physical change; The second is to heat sugar, so that students can know that sugar heating produces new substances through observation and inquiry.

In order to reflect the theme of this activity and let students construct the scientific concepts of physical change and chemical change independently through long-term exploration, I have integrated the teaching materials and put the two exploration activities together, which mainly tend to be considered in two aspects:

First, students' scientific observation activities began to be cultivated as early as the third grade. As a sixth-grade student, they are familiar with such observation, so they can have more time to observe and explore through integration. The difference is that the observation in this class requires students to learn to keep samples for observation. By comparing with the samples, the characteristics of material changes are summarized to guide students to attend classes. However, in the actual observation of students, I found that some students or groups have one-sided observation of the characteristics of things and cannot observe them from multiple angles, thus affecting the progress of observation and inquiry, resulting in too much observation time for "mixed beans" and too little observation time for "white sugar heating".

Second, the scientific concepts of this course "physical change" and "chemical change" are essentially different. Since the needs are different, students should be allowed to compare and discover in observation and inquiry activities. Through integration, students can be provided with more time for comparison and discovery, so that they can explore their own gains. However, in the actual teaching process, there is a deviation in the control of students' independent experiments, which takes too much time and leads to less "comparison" of students. Although students are allowed to compare through actual illustrations (ppt), the time is limited, and this process passes in a hurry, so that the construction of scientific concepts lacks students' "independent consciousness". Moreover, more experimental phenomena in sugar heating have not been discussed, which is obviously not conducive to the construction of concepts.

Through this teaching demonstration, I realized my own problems in teaching, which benefited me a lot in improving teaching.