Scientific concept:
1, the leaves of trees are diverse, and the leaves of the same tree have the same basic characteristics.
2. The leaves of plants are generally composed of leaves and petioles, and there are veins on the leaves.
3. Leaves are alive, too. Leaves begin to grow from leaf buds, and finally age and die, completing a lifetime.
Process and method:
1, counting the number of leaves picked up and the number of leaves;
2. According to certain judgment, it can be divided into the same kind of leaves and different kinds of leaves.
Emotions, attitudes and values:
Cultivate students' interest in learning leaves, and cultivate the attitude and consciousness of caring for the environment and living in harmony with nature.
Teaching emphases and difficulties:
Focus: carry out activities to observe the life phenomenon of leaves, and construct leaves is also a scientific concept with life.
Difficulty: Is it the same leaf?
teaching process
Situation import:
In the nature where we live, students are everywhere. Today, I brought this piece of green to class. Look, is it beautiful? (Courseware) Where is the beauty? Who decorated the beauty of the tree? (mainly the leaves of plants) You observe carefully. Today we are going to study the secret of leaves, that is, the leaves of plants.
The blackboard says: 5 leaves of plants.
(2) Experience inquiry:
Today, the students brought many leaves. How did you collect it?
Default 1: I found it in the Woods.
Presupposition 2: I picked it out on campus.
Teacher: Students, please comment. Which student's behavior is right?
As a result, the students judged that picking flowers and plants was wrong.
One, one, one place:
The teacher knows that everyone likes leaves. Now put the picked leaves on the table and let's play a little game, shall we? Let's compare who has the fastest reaction and the fastest little hand. Listen to needs, ask and show questions:
1 Teacher: How many fallen leaves did I pick up?
Health activities: Counting, placing and reporting quantity.
Teacher: You are all quick. You are all good children. The teacher is really glad to have prepared so many leaves as required.
(Design intention: By counting, students can have a better understanding and love of the leaves in their hands, just like playing with toys. At the same time, this activity is also a small warm-up preparation. Lay the foundation for later activities. )
Teacher: Now the teacher wants to see who is the most observant and who is the careful child.
Teacher 2: Divide it in your own way. How many kinds of leaves are there?
Teachers patrol and guide, encouraging students to divide leaves independently.
Health activities: report
Teacher's camera blackboard writing: shape, size and color
Teacher: The students have thought about it seriously, but the results are different, because the basis of our classification is different.
Teachers use physical projection to show three classification methods respectively.
Teacher: Let's verify which method separates the same kind of leaves.
Biological activity: it depends on the shape to find out whether the leaves are the same.
The teacher concluded that there are many ways to classify leaves, but to get the same kind of leaves, we must classify them according to their shapes.
(Design intention: This is a small scientific inquiry activity. Students use their hands and brains. To classify, they must first observe the characteristics of the leaves in their hands, and on the basis of finding that the leaves are different in size, shape and color, they come to the conclusion that only leaves with the same shape are the same kind of leaves. In the process of this activity, cultivate students to attach importance to evidence and question boldly. )
Teacher 3: How many kinds of leaves are there in our group? (Courseware demonstration needs "warm tips")
Health activities: At first, I was at a loss. Later, some students started to form teams freely, and then cooperated to divide leaves.
Teacher: Organize and help students find partners and cooperate in learning.
Health activities: report classification results.
Teacher's summary: Son, you did a good job and reported everything. Do you like studying in cooperation with your classmates?
(Design intention: On the basis of dividing leaves by yourself, there are several kinds of leaves in a group through group cooperation. In the process of arrangement, students' understanding of leaves is further deepened. This not only consolidates and exercises the classification method, but also cultivates students' awareness of being willing to cooperate with others. )
Second, compare:
Physical projection shows some leaves with different sizes, different colors, incomplete and incomplete, so that children can judge whether they are the same leaf.
1. Question: Are these leaves the same?
Health activities: observation
2. Discussion:
(1) What did you observe that they are the same kind of leaves?
(2) What is observed that they are not the same kind of leaves?
Teacher: What is the basis of your judgment?
Default: Whether the shapes are the same.
Teacher: There is a broken leaf at the intersection of the students' arguments. Guess what this leaf looks like before it becomes incomplete. Ask a classmate to fill in the missing part of this leaf.
Biological activity: Only by observing the same shape can we conclude that they are the same kind of leaves. And we can make up the original appearance of the broken leaf according to other parts, and then judge.
(3) What are the main characteristics of the same leaf?
Biological activity: It is observed that the same leaf has many similar characteristics besides the same shape.
Health activities: see, listen, smell and taste.
Default: there are filaments on the leaves; Leaves have serrated edges. ...
(Design intent: Observation is a basic scientific skill, which allows children to pay attention to nuances, observe with multiple senses, and have a new understanding of leaves. Through observation, students gain knowledge, enjoy learning, learn to learn, learn to listen, learn to share with others, and students become the masters of learning. It doesn't matter if you don't find many, you can naturally transition to the next link and discover the structural composition of leaves. )
3 Comparison: Compare and observe different kinds of leaves. What is the same structure of leaves?
The teacher explained in time: Hold out your little hand and treat your forearm as a petiole. Students will naturally say that the palm is a leaf, and the lines on the palm are equivalent to the veins of the leaf.
(Design intention: Through such an image metaphor, students immediately understand that the vein is not a separate part of the leaf, but a part that grows on the leaf. This design is to let students know the structure of leaves in connection with real life, which is full of childlike interest. )
Third, observe the growth and changes of leaves:
1. Observation: What are the similarities and differences between fresh leaves and fallen leaves? Thinking: What is the biggest difference between fresh leaves and fallen leaves on trees? Yes, fresh leaves are alive and fallen leaves are dead.
2. Description: Observing the leaves of a plant, can we see the growth and change process of the leaves? Can you find some leaves at different growth stages on this branch? (such as leaf buds, leaflets, tender leaves, mature leaves, old leaves, dead leaves, etc.). ) Can you infer the growth process of a leaf from the different growth stages of several leaves?
3. Summary: Leaves are alive, too. They grow from leaf buds to small tender leaves, and then slowly grow old. The leaves of many plants grow from spring to yellow and die in autumn, completing the life of leaves. Although some trees do not shed their leaves in autumn, their leaves also have a complete process of growth and aging.
(3), expand:
Teacher: Do you like leaves? Then don't waste the picked leaves. Spread the wings of imagination, use your dexterous little hands, display your intelligence, choose the way you like, and express your love for the leaves.
Life activities: you can make leaf rubbings, leaf stickers, leaf bookmarks and so on.