The elementary arithmetic with brackets in Unit 1, Volume 2 of Mathematics for the Fourth Grade of Primary School, published by People's Education Press, is a summary of integer elementary arithmetic according to students' understanding of mixed operation and its operation order, as well as the role of brackets.
Second, the teaching objectives
Knowledge and skills: enable students to master the order of two-level operations (including parentheses and brackets) and calculate correctly.
Process and method: Let students actively participate in teaching activities through independent inquiry and cooperative communication.
Emotional attitude and values: cultivate students' consciousness of subject, question, exploration and cooperation. Cultivate students' habit of thinking independently and considering problems from different angles.
First, teaching priorities and difficulties
Key point: Understand the order of the four operations with brackets.
Difficulty: Use brackets to master the order of the four operations.
Fourth, the analysis of teaching methods
Starting from students' thinking reality, stimulate their desire to explore knowledge. The closer the teaching is to students' reality, in the process of guiding students to feel arithmetic and algorithms, let them try, let them actively participate in the formation of new knowledge, and mobilize students to speak their own methods boldly in time. Adhere to the principle of facing all and taking student development as the foundation. Let every student gain something and have the opportunity to experience the joy of success.
Teaching process of verbs (abbreviation of verb)
(A) create a situation to stimulate interest in the introduction
Do you still remember the "Snow World Amusement Park"? Two days ago, we went to the skating area and skiing area, where we explored many math problems. Today, let's take a walk in the ice sculpture area and study the math problems in the ice sculpture area together, shall we? (The courseware shows the scene of the ice sculpture area)
What mathematical information do you learn from the picture? The information given here is that there are 180 tourists in the morning and 270 tourists in the afternoon, and every 30 tourists need a cleaner. According to this information, what math questions can you ask? Students can ask questions freely.
(2) independently explore and solve problems
How to solve "how many cleaners are there in the afternoon than in the morning?" What about this question? Can students express their problem-solving process through formulas? Let the students think independently and write the formula. At this time, the teacher found different solutions by patrolling and asked the students to take out the formulas on the blackboard. Then, they asked the students on the blackboard to talk about their own thinking process, and asked them to explain why brackets were used in 270- 180. Summary: Parentheses are used to change the order of operations.
1, example 4 96÷ 12+4×2 group discussion, operation sequence, student report operation sequence, teacher's summary, students' independent calculation.
2. Add brackets 96 \u( 12+4)×2 to the title. The teacher explained that according to the conclusion just drawn, the students in brackets should try to calculate first.
3. Introducing Parentheses 96÷( 12+4)×2 There are two parentheses in this formula. Guess what? Students express their opinions after thinking, and finally the teacher summarizes the methods.
(3) Consolidate practice and improve feedback.
1, complete the corresponding work and practice the questions in groups.
2. Analyze the wrong questions and improve the ability to solve problems.
(4), the whole class summary, self-evaluation