Instructional design on how substances dissolve in water

First, ask the students to think about the solution, for example, when they drink sugar water, or when they drink salt water when they have diarrhea. At this time, they add salt or sugar to the water, and then stir the tasteless water to become a sweet or salty solution, does that mean that the salt and sugar disappeared, it definitely did not disappear, so you can propose to the students that the dissolution of the substance is actually dispersed in the water and forms a separate molecule, or ion.

Then it can be said that sodium hydroxide is soluble in water and ammonium nitrate is soluble in water, and its thermal effect is different, of course, this can be done by giving students experiments and letting them draw conclusions. In turn, students can understand that there is also a thermal effect when dissolving.

In addition, you can also connect purified water and salt water to the series circuit for students to see, in fact, the conductivity of salt water is much better than that of pure water. The reason why the conductivity is good is that there is a large amount of free charge in the free charge in the brine, that is, sodium ions and chloride ions. That is, ionic compounds can ionize anions and cations when dissolved.

The sucrose solution does not conduct electricity, which proves that when sucrose is dissolved in water, it does not produce a free charge, and the dispersion produces uncharged molecules.

Dissolution means that the substance is evenly and stably dispersed in water, does not settle on its own, and cannot be separated from the solution by filtration. 2.Process and Methods: Observe and describe the dissolution process of potassium permanganate in water, and imagine the dissolution process of table salt.

How much can water dissolve the teaching design is as follows:

Core Literacy Goals.

Scientific concept: through experimental observation, it is known that water can dissolve salt and baking soda; Recognize that the same amount of water is able to dissolve table salt and the quality of baking soda is different.

Scientific thinking: can initially establish an intuitive model to explain the degree of dissolution of a substance in a certain amount of water.

**Practice: Using the method of comparative experiments, the degree of dissolution of substances in a certain amount of water can be observed.

Attitude responsibility: In the observation experiment, willing to share their own opinions, willing to listen to the views of others, and improve and improve the activities of Shanqin**.

Teaching is a major and difficult task.

Important: It was found that different substances dissolve in different amounts in water.

Difficulty: Obtain the amount of salt and baking soda dissolved in 25 ml of water through standardized operation.

Teaching process. 1. Focus: Review old knowledge and reveal the topic (5 minutes by default) Material preparation: 1 beaker filled with water, 1 glass rod, salt] 1.Show the salt and ask: What happens if you put the salt in the water?

2.Looking back at the characteristics of dissolution, let's talk about substances that can be dissolved in water. Can crude substances such as salt and brown sugar dissolve in water all the time?

3.Show baking soda and introduce acquaintance.

4.Reveal the topic: How much can water dissolve?

The purpose of this lesson is to discover the main differences and characteristics between dissolved and insoluble salt, sand, flour, and potassium permanganate by further observing and comparing the different states of salt, sand, flour, and potassium permanganate in water.

Most of the students are not able to observe the process of dissolution in detail in their lives. As a result, there is a lack of perceptual understanding of how matter is evenly dispersed into the water. In this lesson, potassium permanganate, a typical material for dissolution, is used to describe the gradual change of potassium permanganate dissolved in water through careful observation.

Imagine the possible changes that may occur when salt dissolves in water, and gradually form the scientific concept of "dissolution" through the subsequent comparison of the different states of different substances in water.

** is the main way to learn in this science lesson. It can be said that it is an important way for students to acquire knowledge, and it is also the most effective way to internalize knowledge. The formation of the concept of dissolution is gradually refined and established by students after experiencing the first activity.

In my teaching, I provide students with ample opportunities for science, so that they can experience the joy of learning science and increase their scientific knowledge and skills in the process of conducting science.

Through the study of the previous lesson, students know that flour and sand can be separated by filtration, and potassium permanganate can also be separated by filtration? At this time, the students had a collision of ideas and different opinions appeared. I wasted no time in proposing a filtration method, and due to the limitations of equipment and time, I took a group of students to work together to complete the filtration experiment.

Although they were clumsy in filtering, a few made mistakes. But I think it is in this process of continuous improvement and correction that their cognitive ability, hands-on ability and ability are improved.

In the study of this lesson, I think that the students are not very clear when describing the dissolution process of potassium permanganate, some students pour a large spoonful of potassium permanganate into the water at once, and the whole glass of water turns purple at once, resulting in the unclear observation of this process. Some students were in a hurry to stir without waiting for potassium permanganate to enter the water, and they were not accurate enough to describe the phenomenon they saw. Some groups failed to make timely records of the phenomenon after observing it, and the whole experiment process was not compact enough.

But in any case, the primary science curriculum is a science initiation curriculum aimed at cultivating students' scientific literacy. Scientific literacy is long-term and requires us to provide more opportunities for children. We should give students more opportunities to be independent and promote the cultivation of students' scientific literacy, which is also our unremitting pursuit in science teaching.

1. Introduce new courses.

2. Communication: How is table salt dissolved into water? What if you could see the process by which a substance dissolves into water? Please draw your thoughts on the notebook.

2. Learn a new lesson.

a) Observe the dissolution of potassium permanganate.

1. Guided imagination: the dissolution process of table salt in water.

2. Teacher's explanation: In order to clearly observe the dissolution process, we use a colored substance to do the dissolution experiment. The teacher shows potassium permanganate. (The teacher's pick-and-place demonstration should be standardized, this is the first time students are exposed to chemicals).

3. Guided observation description: What kind of substance is potassium permanganate?

4. Student experiment: Gently put a small grain of potassium permanganate in a beaker filled with water, first observe the dispersion of potassium permanganate in water, and then gently stir the water with a glass rod to continue to observe the changes of water and potassium permanganate. (Note the details of the student's observations).

5. Student report: What kind of changes do potassium permanganate have before, during and after entering the water? Does it dissolve in water? What are the similarities and differences between it and the dissolution of table salt in water?