Teaching objectives:
1, which enables students to explore various methods of calculating 8 plus several independently on the basis of existing experience, reflecting the diversity of algorithms; Make students further understand the "plus ten method" and calculate 8 plus several correctly and skillfully;
2. Cultivate students' preliminary observation and comparative 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 emphasis: be able to calculate 8 plus several correctly and skillfully.
Difficulties in teaching: Re-understanding of "Ten-Point Method": Experiencing the diversity of algorithms.
Teaching aid preparation: multimedia courseware
Teaching process:
First, dialogue and exchange, introducing new lessons.
Teacher: Students all know that planting trees can purify the air, beautify the environment, make furniture and make paper. So we should take good care of trees and plant many kinds of trees. Look, Naughty and Xiaoxiao also went to plant trees. (Show courseware)
Second, create situations and solve problems.
1. Look at the picture and ask questions.
Look at the picture and tell me what you know from it.
(Health: Naughty planted 8 trees, and Xiaoxiao planted 6 trees. )
What math questions would you ask?
Students ask math questions.
Teacher: The students are great and ask so many questions. In this lesson, we will focus on solving one of the problems: how many trees are there in a tree? The courseware shows: How many trees are there? )
Design thinking: pay attention to humanistic education in mathematics teaching and cultivate students' problem consciousness. By creating the situation of planting trees with naughty smiling faces, we can guide students to ask math questions according to the situation, stimulate students' awareness of questions, cultivate students' ability to ask questions, infiltrate the education of caring for green flowers and plants, and promote students' active development. )
Third, explore and comprehend the algorithm independently.
(1), students explore independently.
Teacher: Who can work out the formula of this problem?
Student form. There may be: 8+6= 14 or 6+8= 14.
Teacher: 8+6= 14. Oh, you all know his number. How did you work it out correctly and quickly? Can you introduce it to everyone?
Teacher: Now please think about it. How to calculate it? How many ways do you have? Tell your deskmate what you think.
Students think and communicate.
2. Reporting methods
Teacher: Now, please tell the children, what methods did you use?
Student representatives report and exchange. There may be:
Method (1): the method of counting. Count eight trees in the back row and six trees in the front row. A * * * is 14 tree, and 8+6= 14.
Method (2): First give two 6 to 8, then add 4,2 to 8 to get 10, and add 4 to get 14.
Teacher's instruction: add up to ten, look at large numbers and divide them into decimals.
Talk about some classmates and practice speaking at the same table.
Method (3): Counting 6 trees out of 8, 1 * * * 14 trees. 8+6 equals 14.
Method (4): Divide 8 by 4 and 4, 6 and 4 add up to 10, 10 plus 4 equals 14, and the total * * * is 14 trees.
Method (5): According to 9+6= 15, 8+6 equals 14.
Method (6): According to 10+6= 16, 8 is 2 less than 10, so 8+6= 14.
Step 3 choose your favorite method
Teacher: It's amazing that the children have come up with so many calculation methods. We use different methods to calculate that 8 plus 6 equals 14. Which of these methods do you like best? Tell it to your little friend.
Students introduce their favorite methods to each other.
Teacher: Are the children tired after studying for so long? Let's listen to the children's songs brought by the smart dog and relax! (Courseware playback: Add a few to eight, don't be afraid, borrow two, make ten, and then add up the rest, and the calculation will be right and fast. )
Teacher: Let's read it together!
(Design thinking: The new curriculum standard advocates algorithm diversification. This link is based on students' knowledge and life experience, providing students with time and space for independent thinking, hands-on operation and cooperative communication, guiding students to solve problems in various ways and affirming students' reasonable methods. Students feel the diversity of algorithms while experiencing success. At the same time, teachers are not eager to tell students which method is the easiest, but guide students to realize the optimization of the algorithm independently in the practice process, which effectively cultivates the habit of students being brave in expressing, being good at listening and being willing to reflect. )
Third, practical application to solve problems
1. 8 on the left and 7 on the right. How many flowers are there in a * * *? Can you list the formulas? Student form.
Teacher? How do you calculate the result when you add up to ten? Student report.
Step 2 solve the problem
Teacher: In summer, we often see butterflies and butterflies dancing among flowers. (Show the pictures of butterflies and dragonflies) There are 8 butterflies and 7 butterflies flying among the flowers. Can you list two addition formulas?
Students state calculations, and teachers give collective guidance and feedback.
Step 3 give it a try
Teacher: Now, please choose your favorite method from so many methods and try it at the bottom of page 74 of the book. After you finish, you should check carefully and compare which children are the most careful.
Students use their favorite methods to calculate.
Teacher: Have you finished the calculation? Who will tell us how you worked it out? What is your calculation result?
Students' representatives exchange and revise collectively.
Teacher: Are these three questions correct, little friend? Children with mistakes, please do more calculations and correct them.
4. See who is faster:
8+3 8+4 8+5 8+6 8+7 8+8 8+9
Do it yourself. Tell me what the trick is.
5. Teacher: There are a group of cute little animals whispering under the flowers. Who are they? What are you doing? (Showing courseware: Little ants are moving) Oh, little ants are moving!
Teacher: What can we do to help small ants find their own homes?
Students say method, calculate.
Teacher: The students used what they learned to help the little ant find his home. You are really helpful children.
(Design thinking: juniors are young and have short attention time. In order to stimulate students' enthusiasm for learning and participation, in practical application, I designed two scenes as story scenes between butterflies, dragonflies and ants in the garden, so that children can consolidate new knowledge in a relaxed and happy atmosphere. )
6. Buy food.
Teacher: We often go to the supermarket to buy some delicious food. Please 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. )
7. Game: Capture the Red Flag ("Capture the Red Flag" game on page 76 of this book)
Design thinking: the practice of buying food is open to a certain extent. Combined with the characteristics of children, children can consolidate the calculation method in the process of choosing delicious food. After that, practice "8 plus several" in the fierce "Red Flag" competition, and extend the calculation method of "7 plus several". In this process, we also cultivate children's ability to observe, summarize and discover laws, so that students can learn happily. )
8. Small expert in calculation
5+6= 13+5= 9+9=
6+9= 6+6= 3+9=
8+7= 4+7= 8+8=
9+7= 7+6= 2+9=
Students do it themselves and give feedback collectively.
9. See who writes more.
8+()=()
Fourth, the class summary
Teacher: Today we discussed "8+?" What have you gained from the calculation method? 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.