[Teaching objective] 1. Through operation, students are guided to work out the method of calculating 8 plus several by using their existing experience, which reflects the diversity of algorithms, understands and grasps the thinking process and method of 8 plus decimal addition, and correctly calculates 8 plus several.
2. Cultivate students' hands-on operation ability and preliminary observation and comparison ability.
3, can find and put forward simple mathematical problems from daily life and real situations, and can apply existing knowledge, experience and methods to solve problems. In the process of learning mathematics, learn to cooperate with others and get a good emotional experience.
[Teaching Focus] Focus on making students feel the diversity of calculation.
[Teaching Difficulties] We should change according to the changes of students, so that students can take the initiative to learn from their own understanding.
[Teaching means]
Teaching methods: explanation, trial and error, dialogue.
Learning method: group cooperative learning.
Teaching preparation: two bundles of sticks.
[Media Description]
[Teaching time] 40 minutes
[Teaching process]
(A) create a situation, ask questions
Teacher: Students, have you ever been to the park? On Sunday, naughty children also go to the park happily. While playing, he learned a lot of math knowledge and wanted to share it with you. Let's go and have a look with him. Situation 1: Naughty saw the master painting protective paint for the No.8 and No.6 trees on the main road of the park. )
Teacher: What questions can you ask according to the situation that Scampy is counting trees on the road? (According to the questions raised by the students, choose the questions related to the study in this section. )
A * * *, how many trees are there? )
The new teaching concept is to pay attention to students' real life. Here, students love to go to the park to ask questions, so that students can experience the ubiquitous mathematics in life and feel the close connection between mathematics and real life, thus stimulating their enthusiasm for learning. )
(2) independently explore and solve problems
1, students explore independently.
Teacher: Think about it. How many trees are there in a * *? How to solve it? (Students can make: 8+6 or 6+8)
Teacher: How many trees are there? Please think for yourself first. If necessary, you can make a pendulum with your learning tools and calculate it. Leave enough time for students to think, or use school tools to think and calculate. The teacher made a tour to understand the students' learning situation. )
2. Intra-group communication methods.
Teacher: You must have come up with your own good method. Can you talk about your ideas in the group? Let the group leader organize it, discuss the calculation method in the group first, and then select representatives to communicate in the class for a while.
(Students can choose one or several representatives when discussing in groups. Teachers go deep into groups and encourage students to participate in students' discussions in time. )
3, the whole class exchange results.
Teacher: Which group would like to talk about what you discussed? Who wants to add? How is his method? Is there a different way?
Students have the following situations:
(1) from 8 to 8, 9, 10,1,12, 13,14;
(2) Divide 6 by 2 and 4, 8 plus 2 to get 10, 10 plus 4 to get14;
(3) Divide 8 by 4 and 4, add 4 to 6 to get 10, and add 4 to get14;
(4)9 plus 6 is 15, 8 is less than 9 times 1, 15 minus 1 to get14;
(5) 10 plus 6 equals 16, 8 is less than 10 equals 2, 16 equals14;
……
When students report, they can use learning tools to demonstrate and talk, or they can directly dictate. Other students can add, and those who don't understand can ask each other questions. Teachers simply write down their own corresponding thinking process according to the students' situation, affirm or reward the students' academic achievements at any time, and also choose other students for appropriate evaluation. )
(Comment) In this link, students are allowed to calculate 8 plus several in different ways, which fully respects students' choices and embodies the new concept of "algorithm diversification" advocated by curriculum standards. Teachers dare to let go, leaving enough time and space for students to use a variety of sensory learning and communicate with the whole class on the basis of independent thinking, which has a strong sense of hierarchy and effectiveness. When evaluating, we should not only affirm students' problem-solving methods, but also affirm students' labor achievements, so as to improve students' enthusiasm. )
4. Choose the method that suits you.
Teacher: The children are amazing. They have come up with so many methods to calculate. We all use different methods to calculate 8 plus 6 to get 14. Which of these methods do you like best? Why? Please tell your deskmate what you think.
Students communicate at the same table. )
Teacher: Naughty adopted the calculation method of "8 plus 2 10, 10 plus 4 14". Did you find your favorite method? You can do the problem in the way you like.
There are no restrictions on the choice and understanding of various methods, and students are encouraged to choose the way of learning mathematics and understanding knowledge independently to realize personalized learning. )
(3) Practical application, expansion and improvement
1, Baihua Garden.
Teacher: When we walk out of the playground, let's go to Baihua Garden again. Show 75 pages of courseware: butterflies are flying in the flowers and dragonflies are circling in the grass. )
Teacher: What beautiful scenery did you see? What math questions would you ask?
(Students * * * understand the meaning of the picture, calculate 8 plus 7, and instruct students to calculate "4 plus 8" with "8 plus 4" according to the situation. After the students do it right, the courseware shows that the breeze is blowing, the flowers in the garden are more colorful, the music is playing, and the students can rest. )
2. ants can move.
Teacher: We just saw the scenery above the beautiful garden. In fact, there are a group of cute little animals whispering under the flowers. Who are they? What are you doing? (Show courseware: Question 4 on page 75 of Processing, the little ant is moving, explain the requirements of moving. )
Teacher: What can we do to help small ants find their own homes? (After the students answer, the teacher clicks on the courseware. )
Teacher: The students used what they learned to help the little ant find his home. You are really helpful children.
3. Buy food.
Teacher: Naughty took everyone around the park for a while. He wants to invite everyone to a small shop in the park to eat something. Can you help him choose two kinds of food and work out the price? (Show courseware: The prices of food are as follows: candy 6 yuan, bread 3 yuan, juice 4 yuan, hamburger 8 yuan, chocolate 7 yuan, chicken leg 9 yuan, cola 5 yuan. )
(1) Help Scampy choose a hamburger and another food and calculate the price. Students choose and practice the calculation of 8 plus several. )
(2) Choose two kinds of food at will and work out the price. Students can choose to calculate any two numbers. )
The design of the evaluation exercise is lively and interesting. In a pleasant atmosphere, it not only consolidates knowledge, but also improves students' abilities of observation, thinking, hands-on and problem solving, and cultivates students' interest and confidence in learning mathematics. In particular, the design of the practice of buying vegetables has made different students develop differently. )
4. Class summary.
Teacher: Today we went to the park with Scampy. What did you get? There is more knowledge worth learning in our life. The teacher believes that you will gain more on the road of growth through your own observation and efforts.
[Blackboard Design] How many trees are there?
8 + 6 = 14 8 + 6= 14