Teaching emphasis: understand the concepts of volume and volume (the size of the space occupied by an object is called the volume of the object; The volume of the object that a container can hold is called the volume of the container. )
Difficulty: distinguish between volume, volume and area.
Preparation before class: plastic bags and cups filled with water.
Teaching process:
Understanding space
Question 1: What is space?
The teacher writes "space"
Teacher: Who can explain the meaning of space?
Master: Space is a place where many things can be put.
Xin: Space is in an object.
Bo: Space is a range.
Analysis: Students have been in space, but they don't know how to explain it. In students' answers, space is a place, and "place" can be used instead of "space". We are all used to using one word to explain another. But place can be understood as both space and surface. It can be seen that students are confused about the concepts of "space" and "surface". So, how do students separate "space" from "place"?
Question 2: Where is the space?
Teacher: Please give an example. Where is the space?
Leon: Our classroom is called space.
Ya: There is still room in the desk drawer.
Sim: The inside of the suitcase is called space.
Kun: Plastic bags are called space.
Sweets: There is still room in the chalk box.
Analysis: Through examples, students have a correct understanding of the concept of space, which shows that it is more appropriate for students to learn abstract concepts through examples.
Teacher: What's in the chalk box?
Sweet: chalk
Teacher: Then who is this space reserved for?
Sweet: chalk
Teacher: In other words, who occupies the space of the chalk box?
Sweets: Chalk occupies the space of the chalk box.
Teacher: Does that chalk box take up space? Whose space is it?
Hao: The chalk box takes up the space in the classroom.
Teacher: Whose space does the classroom occupy?
Zhe: The classroom occupies the whole teaching building.
Teacher: Who occupies the space in the drawer?
Pool: School supplies occupy the space in the drawer.
Teacher: Whose space does the drawer take up?
English: Drawers occupy the space of desks, and desks occupy the space of classrooms.
Teacher: We found that what we could see occupied?
Shengqi answered: They all take up space.
Teacher: What conclusion can you draw?
Han: Everything takes up space.
Analysis: Students began to look for space and found that any object occupied space, and space began to be understood by students.
Question 3: What are the properties of space?
Teacher: (inviting two boys with significant physical differences to the front of the classroom) Students, who is the older of these two students?
Student: Xu Da.
Teacher: What is the essence of describing a tall and burly person?
Student: It is Xu who takes up a lot of space.
Teacher: So the attribute of space is size.
Analysis: Combining the knowledge that all objects occupy space, starting from the experience of head size, let students understand that the attribute of space is size.
Question 4: What are the connections and differences between space and surface?
Teacher: We have studied "surface" before. Is there a difference and connection between surface and space?
Bo: The surface is only long and wide, and the space is long, wide and high.
Teacher: Is there another way to put it? Observe our classroom. Where is the space? Where are the noodles?
Chao: There are six faces in the classroom. These six faces form a space.
Teacher: So what's the connection between space and surface?
Heng: Space is surrounded by faces.
Teacher: Now we understand that all objects occupy space and that the attribute of space is size. We combine these two kinds of knowledge to form a new mathematical knowledge-volume. (blackboard writing: the size of the space occupied by an object is called the volume of the object), because any object has its own volume, it will occupy a certain space.
Analysis: When students find that the surface is surrounded by space, the space and the surface will be separated from the chaotic state, so as to avoid the confusion of area, surface area and volume in future study.
Understanding volume
Teacher: in life, some objects just occupy space by themselves; For example, some objects occupy a space by themselves and leave a space for others.
Sen: The chalk box takes up space, leaving space for the chalk; Chalk only takes up space
Han: Drawers take up space, leaving room for textbooks; Textbooks only take up space.
Ya: the refrigerator takes up space and leaves room for food; Food only takes up space.
Teacher: This kind of thing that can hold things in it is called a container. What is the interior space?
Bo: This is called its capacity.
Teacher: We call this the internal space volume.
Teacher: Teacher Qin's quilt is full of water, which can hold 300 ml of water. What can we say?
Zhe: The volume of the cup is 300 ml.
Teacher: What else can I say?
The volume of water is 300 ml.
Teacher: The volume of the cup is 300 ml. Is the volume of the cup 300ml?
Day: No, the volume of a cup must be more than 300 ml. Volume is the space occupied by the whole cup. Volume only considers the space inside the cup. Because all objects have thickness, the volume of an object is greater than its volume.
Analysis: As a concept, volume can be understood through examples. After understanding, it is given a name-volume, and the difference between volume and volume is analyzed through students' experience.
practise
Are we talking about volume, volume or area in the following statements?
1. Miss Qin has 100 ml of water in her cup.
This coaster is too small.
This water cup is the biggest.
The lid of this cup won't close.
Miss Li's glass can hold 2 liters of water.
Analysis: Use these topics to consolidate students' understanding of the important and difficult knowledge in this lesson.
Postscript: Pupils do not enter the classroom with a blank sheet of paper, but with their own "understanding". How to transform students' understanding into mathematics understanding and teachers' understanding is one of our task in preparing lessons.