Tisch
Teaching objectives:
1, understand the meaning of negative numbers in familiar life situations, and be able to read and write negative numbers.
2. I will use negative numbers to represent some quantities in daily life and realize the application value of mathematics.
3. Get a successful experience in the process of understanding and applying negative numbers to solve problems, and strengthen your confidence in learning mathematics well.
Teaching focus:
Consolidate the understanding of negative numbers.
Teaching difficulties:
Master the quantity that positive numbers and negative numbers represent opposite meanings.
Teaching aid preparation:
multimedia courseware
Teaching methods:
Self-study teaching materials and organize consolidation exercises.
Teaching process:
First, sort out the knowledge.
1, carefully read the contents of the textbook from page 87 to page 9 1, and recall the knowledge about negative numbers.
(1) illustrate how to read and write positive and negative numbers. What should I pay attention to when writing positive and negative numbers?
(2) Why is 0 neither positive nor negative? Positive numbers are all _ _ 0; Negative numbers are all _ _ _ 0.
(3) Which two quantities do positive numbers and negative numbers represent respectively? Can you give an example from your life?
2. After 4 minutes, communicate with each other in pairs. If you have any questions, you can discuss them in groups!
3. Summary: The numbers we dialed are +3,+15,+8844.43, etc. Positive number; Numbers like -6,-10,-155 are called negative numbers. 0 is less than all positive numbers and greater than all negative numbers. 0 is the dividing point between positive and negative numbers. 0 is neither positive nor negative.
Positive numbers and negative numbers represent two quantities with opposite meanings.
Second, basic exercises.
1, display 1
(1) If 30m forward is marked as +30m,-20m means (), and 10m backward is marked as ().
(2) If +60m means an increase of 60m, then -60m means () and a decrease of 50m means ().
(3) If+120m means eastbound 120m, then-70m means () and 50m means westbound ().
Requirements: 1, do the questions independently.
After writing, the students check each other.
3. Display 2
(1) Read and fill in.
37,-78,+20,-5,0,+ 12 1, 98, - 1000, - 13, 34, -34。
Negative positive number
Finally, there is an unfilled number left in the box above. This number is ().
(2) Three classes in Grade 6 take a quiz. If they answer correctly 1 get 10, if they answer incorrectly 1 deduct 10, they will not get 0. It is known that Class One answers correctly 1, Class Two answers wrongly 1, and Class Three answers correctly and wrongly 1. Please write down the scores of these three classes.
1 class () is divided into 2 classes () and 3 classes ().
Third, improve the practice.
(1).
1. If southbound 50m is marked as -50m, northbound 40m is marked as (), and 45m means ().
2. If the expenditure of 180 yuan is recorded as-180 yuan, then the income of 800 yuan is recorded as (), and -200 yuan means ().
3. If the counterclockwise rotation 28 is marked as +28, then the clockwise rotation 16 is marked as (), and+16 means ().
(2) do it.
1, the students used the rest day to help fruit farmers pick apples, and the apples picked from four apple trees were put into four piles. Fruit farmers estimate that each tree can produce apples 100 kg. Students take this estimated value as the standard, and the excess kilograms are recorded as positive, while the insufficient kilograms are recorded as negative.
(1) How much do these four piles of apples weigh?
(2) How many kilograms do these four piles of apples weigh on average? Compared with Wang's estimation, our results are expressed by positive and negative numbers.
2. The height of a group of eight students is as follows.
(1) Calculate the average height of 8 people.
(2) If the average height is 0, the height of each student is represented by positive and negative numbers.
(3) A difference of 0cm from the average height in the above table indicates (); The difference with the average height is positive, indicating (); The difference from the average height is negative, indicating ().
After discussion and collective evaluation at the same table, the students completed it independently.
Fourth, class summary.
Students, what have we gained in this class? Is there a problem?
Verb (abbreviation for verb) class assignment
homework
Blackboard design:
Preliminary understanding and review of negative numbers
Numbers like +3,+15, +8844.43 ... are called positive numbers;
Numbers like -6,-10,-155 are called negative numbers.
0 is less than all positive numbers and greater than all negative numbers. 0 is the dividing point between positive and negative numbers.
0 is neither positive nor negative. Positive numbers and negative numbers represent two quantities with opposite meanings.
extreme
Teaching objectives:
1. Know the negative number and its significance in real situations, understand its generation and function, and feel the convenience brought by its use.
2. Be able to read and write positive and negative numbers correctly, and know that 0 is neither positive nor negative.
3. Make students experience the close relationship between mathematics and life, stimulate students' interest in learning mathematics, and cultivate students' awareness of applying mathematics.
Teaching focus:
The meaning of negative numbers and their reading and writing.
Teaching difficulties:
Understand that 0 is neither positive nor negative.
Teaching aid preparation:
multimedia courseware
Teaching methods:
Teachers' teaching and cooperative communication
Teaching process:
First, check the import.
Question: What numbers have we learned?
Teacher's summary: In order to meet the needs of real life, when counting the number of objects, 1, 2, 3 ... appears natural numbers, and when there is no object, it is represented by natural number 0. When measuring or calculating, sometimes we can't get integers, so we use fractions or decimals to express them.
Ask a question: Who is the smallest number we have learned? Is there a number smaller than zero?
Second, create situations and learn new knowledge.
1. Teaching examples 1.
(1) program: A scene of CCTV weather forecast, the host said: "Harbin is MINUS 6 to 3 degrees Celsius, Chongqing is 6 to 8 degrees Celsius ..."
Students, you must be quite familiar with the content in the situation, right? Can you tell us what the sentence "Harbin is 6 to 3 degrees below zero" means?
Why did my aunt say -6℃ and the subtitles on the screen changed to -6℃?
It's 6 degrees below zero here, and 6 degrees above zero. Can you write them all at 6℃?
Do you have any concise ways to show their differences?
The teacher summed up: the students' ideas are all very good. At present, the international mathematics community uses symbols to distinguish. We use the number with "-"to indicate the temperature below 0 degrees Celsius. For example, we record minus 6 degrees Celsius as minus 6 degrees Celsius and read it as minus 6 degrees Celsius. 6℃ above zero is recorded as +6℃, and the reading is +6℃ or 6℃.
(2) Consolidate practice.
Students, can you use the knowledge we have just learned to represent the temperature with appropriate numbers? Give it a try.
Students finish the exercise on page 87 independently.
Teachers patrol, individual counseling, collective correction of writing is correct, and let students read together.
2. Self-study example 2. (Further understanding of positive numbers and negative numbers)
Teacher: Students, do you know? Mount Everest, the highest peak in the world, has a great temperature difference from the foot of the mountain to the top of the mountain, which is related to the altitude. Recently, the State Bureau of Surveying and Mapping announced the latest elevation of Mount Everest.
Today, the teacher also brought an elevation map of Mount Everest. Please have a look. (The elevation map of Mount Everest, the left part of the textbook page 87, with no symbol before the number) What do you understand from the map?
Guide students to communicate: Mount Everest is 8844.43 meters above sea level.
Let's look at the elevation map of X Turpan Basin in Xinjiang. (The altitude of Turpan Basin, the right part of page 87 of the textbook, with no symbol before the number) What can you understand from the picture?
Guide students to communicate: the altitude of Turpan basin 155 meters.
Teacher's summary: Mount Everest is above sea level, and Turpan Basin is below sea level. Think again: can you record the altitude of these two places in a simple way?
Student exchange: The elevation of Mount Everest can be recorded as +8844.43 meters or 8844.43 meters. The elevation of Turpan basin can be recorded as-155 meters. (blackboard writing)
The teacher asked: How did you come up with this method to record?
Finally, the teacher changed the number to: altitude +8844.43 meters or 8844.43 meters; Altitude-155 meters.
Teacher's summary: Taking the sea level as the boundary, the number of +8844.43 meters or 8844.43 meters means that it is 8844.43 meters higher than the sea level; The number-155m means155m below sea level.
(2) Consolidation exercise: Try it on page 88 of the textbook.
3. Discuss in groups and summarize the positive and negative numbers.
Teacher: Through the study just now, we collected some data. (Show) We can use these numbers to indicate the temperature above zero and below zero, and also to indicate the altitude above sea level and the altitude below sea level. So if you look at these numbers, are they the same? How to classify them?
Ask a question: What kind does 0 belong to? Guide students to debate and express their views.
Summary: (combined with the figure) We observe from the thermometer that 0℃ is the dividing line, the temperature above 0℃ is represented by a positive number, and the temperature below 0℃ is represented by a negative number. Similarly, taking the sea level as the boundary, we use positive numbers to indicate the height above sea level and negative numbers to indicate the height below sea level. 0 is like a dividing line, separating positive numbers from negative numbers. It belongs to no one. But for both positive and negative numbers, it is essential. We call numbers like +6, 3, +8844.43 positive numbers; Numbers like -6,-155 are called negative numbers; And 0 is neither positive nor negative. (blackboard writing)
Usually the plus sign can be omitted. Can the minus sign be omitted? Why?
Finally, let the students read and tick, and think about what numbers the two "……" still represent. (Let students have a more comprehensive and profound understanding of positive and negative numbers)
Third, the use of new knowledge, classroom assignments
1. Problems in classroom activities 1. Let the students read it by themselves first, and illustrate what it means with examples. After the class is revised, please choose five people at the same table to talk to each other.
2. Class activities 2. Discuss at the same table first, then give feedback.
Four. abstract
Students, today we know negative numbers. What did you get?
Verb (abbreviation for verb) class assignment
Exercise 22, questions 1 and 4.
Homework: Exercise 22, Questions 2 and 3.
Blackboard design:
A preliminary understanding of negative numbers
Positive numbers: 20,22, 14, +8844.43…
0: It is neither positive nor negative.
Negative numbers: -2, -30,-10,-15,-155. ...
Tisso
Teaching objectives
1. Know the negative number and its significance in real situations, understand its generation and function, and feel the convenience brought by its use.
2. Be able to read and write positive and negative numbers correctly, and know that 0 is neither positive nor negative.
3. Make students experience the close relationship between mathematics and life, stimulate students' interest in learning mathematics, and cultivate students' awareness of applying mathematics.
Teaching focus
The meaning of negative numbers and their reading and writing.
Teaching difficulties
Understand that 0 is neither positive nor negative.
teaching process
First of all, stimulate interest and introduce new lessons.
Game: I change, I change, I change.
When the teacher says a word, ask the students to say a word with the opposite meaning.
Second, create situations and learn new knowledge.
1. Teaching examples 1.
(1) courseware demonstration: a scene of CCTV weather forecast: Harbin is MINUS 6 degrees Celsius to 3 degrees Celsius.
Can you express these two temperatures in your own way?
Students give feedback after thinking, and teachers prompt, evaluate and guide them in time.
Teacher's summary:
(2) Consolidate practice.
Students, can you use the knowledge we have just learned to represent the temperature with appropriate numbers? Give it a try.
Students independently complete the exercises on page 123.
Teachers patrol, individual counseling, collective correction of writing is correct, and let students read together.
2. Self-study example 2.
Teacher: Students, do you know? Mount Everest, the highest peak in the world, has a great temperature difference from the foot of the mountain to the top of the mountain, which is related to the altitude. Today, the teacher brought an elevation map of Mount Everest. Please have a look. The courseware demonstrates the elevation map of Mount Everest. The left part of the picture on page 124 of the textbook has no symbol before the number. What do you understand from the picture?
Guide students to communicate: Mount Everest is 8844.43 meters above sea level.
Let's take a look at the elevation map of Turpan Basin in Xinjiang. Courseware demonstrates the altitude of Turpan Basin, and there is no sign in front of the number on the right side of the picture on page 124 of the textbook. What can you understand from the picture?
Guide students to communicate: the altitude of Turpan basin 155 meters.
Teacher's summary: Mount Everest is above sea level, and Turpan Basin is below sea level. Think again: can you record the altitude of these two places in a simple way?
Student exchange: The elevation of Mount Everest can be recorded as +8844.43 meters or 8844.43 meters. The elevation of Turpan basin can be recorded as-155 meters. (blackboard writing)
The teacher asked: How did you come up with this method to record?
Teacher's summary: Taking the sea level as the boundary, the number of +8844.43 meters or 8844.43 meters means that it is 8844.43 meters higher than the sea level; Numbers like-155m mean that it is lower than sea level 155m.
(2) Consolidation exercise: Try it in the textbook 124.
Teachers patrol collectively to review.
3. Discuss in groups and summarize the positive and negative numbers.
Teacher: Through the study just now, we collected some data. (Courseware display) We can use these numbers to represent temperatures above zero and below zero, as well as heights above and below sea level. So if you look at these numbers, are they the same? How to classify them?
Students exchange and discuss.
It is pointed out that +8844.43 meters can also be written as 8844.43 meters, so both positive and negative symbols can be grouped together.
Ask a question: What kind does 0 belong to? Guide students to debate and express their views.
Summary: (combined with the figure) We observe from the thermometer that 0℃ is the dividing line, the temperature above 0℃ is represented by a positive number, and the temperature below 0℃ is represented by a negative number. Similarly, taking the sea level as the boundary, we use positive numbers to indicate the height above sea level and negative numbers to indicate the height below sea level. 0 is like a dividing line, separating positive numbers from negative numbers. It belongs to no one. But for both positive and negative numbers, it is essential. We call numbers like +6, 3, +8844.43 positive numbers; Numbers like -6,-155 are called negative numbers; And 0 is neither positive nor negative. (blackboard writing)
Usually the positive sign can be omitted, and the negative sign can also be omitted. Why?
Third, consolidate practice and deepen understanding.
1. Classroom activities: 1, 2 questions.
Read and discuss.
Students read together to consolidate negative reading.
(2) According to the information in the question, talk about three kinds of answers.
Students discuss and give reasons.
2. Exercise 25: 1, 3 questions.
Practice independently and exchange feedback.
Fourth, contact with life and expand applications.
Say: where will negative numbers be used in life?