Tisch
Teaching content:
P2 ~ 3 and P4 do exercise 1 1 and 2.
Teaching objectives:
1. Knowledge and skills: Through practical activities such as taking a look, comparing and measuring, we can know the length unit centimeter, initially establish the expression of 1 centimeter, and can measure the length of an object (limited to the whole centimeter) with a ruler.
2. Process and method: Through students' observation, inquiry and other learning activities, let students establish their understanding of length units in their own creative activities.
3. Emotional attitude and values: experience the connection between mathematics and life and cultivate students' innovative consciousness.
Teaching focus:
Establish the concept of length of 1 cm.
Teaching difficulties:
Measure the length of an object with a student's ruler (only the whole centimeter)
Teaching process:
First, introduce a conversation
Students, who is taller than mother and teacher? Who is short?
How much higher? How much shorter? Make a gesture. Can you know exactly how tall and how short?
"How tall" and "How short" are actually comparing the length of the human body, which requires the use of length units.
Second, explore new knowledge.
(1) unified unit of length
How did the ancients do it when they didn't invent the unit of length?
(Example 1 scene diagram. ) What information have you learned by observing these pictures?
Guide the students to say: the ancients measured the width of the stone with open arms and used one
"or foot length" is the length of a standard object.
What do you think of their methods?
The teacher concluded: In fact, each of us carries several rulers. The length of an object can be measured by one step (ZH ǐ), one step and one step (tu ǐ). Thousands of years ago, the ancients came up with many such methods to measure objects. Now let's measure the length of this table with one foot. Teachers and students measure the length of desks. )
The teacher asked a question: I only measured 3 feet. We all measure the same table. Why is the result different?
Let the students fully express their opinions, and let them gradually understand that the length of each foot is different, and the measured results are different.
Follow-up: How can we get the same result? Is there any good way?
Teacher's summary: Because the standards used in the measurement are different, their length units are also different, so the measurement results may be inconsistent with the facts. This requires a unified unit of length. Let's get to know the length together in this class.
(B) overall perception, understanding centimeters
1. Observe the ruler and know the scale.
Some of these vertical lines are long and some are short. We call it a tick mark. Each number points to a relatively long tick mark. The first number is O, so we call this scale O scale ... What about the back? (Scale 1 ...) Let's read these scales.
There is such a letter on the ruler-cm, and some students have the word "cm" on the ruler. In fact, cm is
It means centimeters. "centimeter" is a unified unit of length. Measure the length of a relatively short object, usually in centimeters.
2. I know 1 cm.
The teacher pointed out: this scale 0 is very important, it is like the starting line, which means starting from here. Congke
The length from 0 degree to the scale 1 is 1 cm. (blackboard writing: 1cm)
Which section of the ruler is also 1 cm in length? Who will point it out?
The teacher demonstrates (gestures) while explaining: the length of this big grid from level 2 to level 3 is L cm, and the length of this big grid from level 3 to level 4 is also 1 cm. What about grades 4 to 5? What did we find? The length of each large cell is 1 cm. Because the length of each grid is the same, we have a unified standard when measuring the length of an object with a ruler.
Students, what do you think of the length of 1 cm? (It's very short. ) Yes, 1 cm is really short.
Follow-up: What objects in life are about 1 cm in length? Let the students speak freely. )
The teacher's courseware shows the width of index finger, the width of Tian Zige and the length of thumbtack.
In a word, the width of our index finger is about 1 cm. Can you also say a sentence in l centimeters?
3. Know a few centimeters.
Teacher: Just now the students met 1 cm. Now the teacher will increase the difficulty. How many centimeters is the length from 0 to 3 and from 0 to 7?
4. Teaching Example 3 (Measure a quantity).
(1) Take out the things prepared before class.
Note, draw its length by hand and say how many centimeters it may be. The teacher demonstrated while explaining: aim the scale O of the ruler at the left end of the note, and then look at the right end of the note. This bill is several centimeters long. Remind students to put the ruler flat on the edge of the measured object and measure along the straight edge of the object, and press the ruler tightly when measuring.
(2) If the ruler is broken and the minimum scale is 2, can you still measure the length of this note? How to measure? (aim the scale 2 of the ruler at the left end of the note, then look at the right end of the note, and subtract a few from the big number, which is the length of the note. )
Third, consolidate the practice.
1. Complete "Doing" on page 4 of the textbook.
Let the students look at the scale, say the length of the pencil, and then say what they think.
2. Complete the first 1 question in the textbook Exercise 1. Estimate a few centimeters before measuring.
3. Complete the second question in the textbook "Exercise 1".
Look at the scale on the ruler and tell how many centimeters the width of the palm and the length of one foot are.
Note: If it is close to 8 cm, we say it is about 8 cm.
Fourth, class summary.
What impressed you the most in today's math class? What are you going to say?
Blackboard design:
Uniform length unit identification centimeter
When measuring, different standards have different results-uniform length unit cm.
A relatively small object can be measured in centimeters.
Measurement method: aim the scale o of the ruler at one end of the object, and the other end of the object faces several meters. The length of this object is several centimeters.
extreme
Teaching content:
Unified length unit
Teaching objectives:
1. Students experience the formation process of length units, understand the necessity of unifying length units, and understand the functions of length units.
2. Ask students to measure the same length with different items in specific activities.
3. Experience the necessity of unifying length units.
Key points and difficulties:
Students use different items as measuring units to measure the same length in specific activities, so as to experience the necessity of unifying length units.
Teaching preparation:
Round, square, triangle, paper clip, pencil, eraser, etc.
Teaching process:
First, the scene import, stimulate interest
Dialogue: The teacher wants to know the width of this math book. Can you help the teacher figure out what to do?
Students use their imagination to express their views.
[Design Intention]: Introduce familiar things around students and stimulate their interest in learning.
Second, organize activities and experience mathematics.
(1) Organize students to measure the same length with different items.
1, the teacher defines the method of activity first.
(1). As a standard, items should be placed one by one, flat and straight.
(2) With four people as a group, each student chooses a different project from four projects (circle, square, paper clip and triangle) to measure.
(3) After the measurement, the four-person group communicates and reports their own measurement results, and thinks: Why do they all measure the width of the math book, but the measurement results are different?
2, student activities, teacher patrol guidance.
3, the whole class exchange report. The conclusion is that the results of quantity are different because different items are selected as standard measurement.
4. Ask students to choose the same thing to measure and show their measurement results.
The conclusion is that in order to get the same result, we should choose the same project as the measurement standard.
(2) Organize students to use items of different lengths as standard quantities.
1. Ask students to choose different objects (such as erasers, pencils, paper clips or by hand) to measure the length of desks, pencil cases and other objects.
2. Communicate and show the students' measurement results to inspire students to ask questions.
For example, why is the width of a math book the length of five paper clips and the pencil case the length of five erasers, but their lengths are different?
Why is the desk longer than the pencil case, but the desk is only four pencils long and the pencil case is five erasers long?
Guide primary school students to realize that because the measurement standards are different and the length is different, the measurement results may not be consistent with the facts.
Let the students use the same object (square) as the unit of measurement to measure objects of different lengths and see what the result is.
Experience the necessity of unified length units.
[Design Intention]: Teaching organizes and helps students understand the necessity of unified length units from two aspects. Let the students measure the width of the math book with different items as the standard in specific operation activities, and then measure different lengths with different items as the standard. This has caused cognitive conflicts and experienced the necessity of unifying length units.
Third, practice consolidation and practical application.
1. Do the problem 1. Look at the picture. Visually, each vegetable is about several squares long.
Students finish independently before communication.
If students can't clearly see which square the right end of the top vegetable is aimed at, they can compare the vertical lines of the squares with a ruler.
2. Do the second question and ask the students to measure the length and height of the table and the height of the stool with a pencil.
The method of determining the quantity is different from the previous one. Don't put the standard items one by one, but let the students measure them one by one to see how long the measured objects are.
3. Do the third question. Students look at pictures intuitively. First estimate the number of cubic meters of the measured object, and then measure it in your head by the method of the previous question.
If students have difficulty in measuring pictures, they can also use cubic objects to measure them. Remind students to pay attention to the measurement method when measuring in kind: the left end of the object should be aligned with the left end of the measured object, so that the measurement result is more accurate.
[Design Intention]: Practice in different ways, so that students can experience the necessity of unifying length units again in specific activities.
Fourth, class summary.
What impressed you the most in today's math class? What are you trying to tell me?
Five, in-class exercises
Tisso
Teaching objectives:
Knowledge points:
1. Let students experience the process of forming length units and understand the necessity of unifying length units.
2. Through activities, make students know the length unit centimeter, initially establish the concept of 1cm, and initially learn to measure the length of an object with a scale.
3. Cultivate students' estimation consciousness and ability.
Ability point:
Cultivate students' ability of observation and operation.
Moral education point:
Make students develop serious and serious study habits.
Teaching focus:
Through the activities, let the students know the length unit of centimeters, and learn to measure the length of objects with a scale.
Teaching difficulties:
The concept of length of 1 cm is initially established to cultivate students' estimation consciousness and ability.
Teaching mode:
"Independent inquiry" teaching mode.
Teaching aid preparation:
All kinds of rulers, coins, paper clips, cubes with a length of 1 cm, etc.
Teaching process:
First, create a situation:
Teacher: Mom needs to buy an elastic band. How long will it take? The teacher measured it, which is as long as the stick on your desk. Please select a physical object for each group to measure.
Students report the results.
Q: It's strange that elastic belt with the same length has different results.
Teacher: What tools should we use if we want to get a unified result?
Health: Ruler.
Second, independent inquiry:
1, I know 1 cm.
Take out a ruler and have a look. What did you find?
Students observe and report.
First, the number, read in order. Q: What is the leftmost position? What does the zero on the ruler mean? This is called zero scale.
B, lines, long and short, are called tick marks.
C, the letter "cm" stands for centimeter, which is a commonly used unit of length.
How long is a centimeter? (The length between scale 0 and scale 1 on the scale is 1 cm. )
Find 1 cm on your ruler. Which paragraph is 1 cm? What did you find? (each grid is 1 cm)
Find and compare what other objects around us are about 1 cm in length.
Hand-painted length of 1 cm. Close your eyes and think about how long 1 cm is.
2. Know a few centimeters.
Teacher: We know how long 1cm is, and how long are 2cm and 3cm?
Q: How many centimeters are two 1cm? How many 1 cm are there in 4 cm? Can you point out the 6 cm part of the ruler?
3. Use centimeters.
Hold up the blue note and estimate how many centimeters it is.
Measure it with a ruler. Fill it in the book.
Measure the length of the elastic band.
Third, expand the application:
1. Is the following measurement method correct? Explain why.
(1) is not aligned with the 0 tick mark.
(2) correct.
(3) measurement is not started from zero scale.
2. What should I do if the front of the ruler is broken and I can't see the 0 scale line?
3. The amount of group cooperation defines the length of the object.
The teacher wants to measure the length of a wrist. It is inconvenient to measure with a ruler. Do you have a good method? (Introduce all kinds of rulers)
5. Choose a ruler and measure the object you are interested in.
Collect information after class: What other units of length do you know?