Tìm số trung bình cộng ( Tiết 1) Toán 4/ Cô giáo Mai Xuân

Welcome children to a class on developing creative thinking skills that connect mathematics to real life Now children study within the reach of a filial child Today the children will explore a primary school math topic—math about common factors The children will continue practicing focused learning skills Before studying be certain to remember this key insight: Dear children when we consciously project such a clear perception of truth Our brain receives information and quickly transmits it to various parts of the body—namely the eyes ears hands and mouth And all these parts will come together around what you desire Then they will assist each other in exchanging information helping the child achieve the lesson's objective And Ms Duân also wants her children to remember a very important formula so that we can carefully examine mathematical problem-solving skills as well as all other skills in life That is practicing skills along with the ability to do them will result in mastery This practice means that children must grasp the methods and approaches To complete a math problem or solve a question we must understand the methods for solving it And then we'll practice using that method that approach repeatedly across different types of problems Then when we practice consistently repeating the same thing over and over aga Then your children will develop not only math skills but also essential life skills So today you'll begin experiencing the method that Teacher Duân has just shared Today's lesson your children will complete the following objectives The first objective is that your children will review We fully understand the meaning and value of the arithmetic mean and secondly the children will master the skill of finding the arithmetic mean various types of exercises at different levels and the third goal that Ms Duân wants is for the children to persevere en we see that we have a method for solving math problems—that is the skill of imaginative thinking connecting mathematics to real life As artists guiding us into the mathematical picture in the exploration section we also begin experiencing the first problem Every morning I go exercising with my mother When reading this sentence we immediately picture a student going for morning exercise with their mother Mother gave me a math problem On the first day the child walked for 20 minutes Under these conditions we can determine tha The time she spent walking on the first day was specifically 20 minutes On the second day she walked 10 minutes longer than on the first day Under these conditions we observe that the number of hours she spent traveling on the second day is hidden within the math lesson more prominently And the children remember that we must always find the time the way of thinking about time that he spent on the second day By taking 20 boys the third day's count is double that of the first day and the third day also conceals time And hidden within the lesson on multiplying a number by a certain number of times is the idea that doubling means multiplying by two so we must always think in this way The time she spent walking on the third day is exactly twice the time she walked on the first day Mom challenges you: if the child walks the same amount each day How much time does your child spend each day When reading this problem's requirement The children should immediately recognize That is the problem of finding the average of multiple numbers and the numbers in question are The time she spent exercising in the morning over three days That's what we'll Using the same formula and method for calculating the arithmetic mean we first find the sum of all the numbers involved then divide that sum by the total count of numbers participating And specifically here we will begin by directing the calming mental command to filter out everything we have just thought about We reconnect and begin Solving the problem The first step is for the children to The time he spent traveling on day two How many minutes did the child travel on day two Add 20 and 10 to get 30 minutes And on the third day the child traveled a number of minutes equal to twice the first day's time doubling that gives us 40 minutes and at this point we can easily determine the answer The result of the problem If the child travels the same distance each day Then the time taken will be The sum of the three days divided by three In 30 minutes Ms Xuan also wants to remind the children that this 30 minutes is precisely the average of the three numbers To help our children remember us we'll keep using harder math problems —this is the problem Alright let's begin Then let's explore How about the next math problem shall we Problem 1 Also wants to secure the foundation for the children Master the basics of math thoroughly So that when we practice test questions The child could excellently complete this problem: find the average of the numbers 1 5 8 and 10 All we need for this problem is to remember the formula we can just pick up our pen and start writing This number is the arithmetic mean So based on these two examples Example 1 and Exercise 1 Teacher Xuan would like to summarize for you To solve average-related problems the first step is for students to identify the objects involved in the problem Or the terms involved in the problem and must clarify exactly how many of each quantity there are then we will proceed to find The sum of the terms Participated Then we divide the sum by the number Of participating terms Actually finding the average number This is the formula as well as the general steps Helping children remember it Let's work through the problem together and connect more smoothly By the second problem you've already heard it —this story has been shared by Ms Xuan Made a new video on my channel The story of mindset Exploring the concept of average And here's the applied problem The lifespans of the three revered monks Were The first lived to be 90 years old The second reached four-fifths The lifespan of the first person When reading these two conditions We immediately recognize The lifespan of the first person Now it's confirmed they're exactly 90 years old The second person to live the longest Reached four-fifths The lifespan of the first person Then Ms Xuan asked the students: When encountering a math problem with a condition in the form of a ratio like this how should you determine it The words presented Before this fraction Its value is from the number The second person lived to four fifths The age of the first person That means the second person's age divided into four equal parts equals the first person's age It will be 5 parts like this And these 5 parts correspond to 90 years Correct right So we'll want to find 4 parts Then we take 90 years divided by 5 to find the value of one part so with 4 we can also determine it The lifespan of the second person Or children can rely on Problem type In grade 3 it involves finding a fraction of a number We take four fifths multiplied by 90 and we arrive at the result— the second person's lifespan Math class has taught us this next step And the third person lived to be 90 years old That's a concrete number now We can't calculate any further can we So when we Use this method Imagine the connection between mathematics and our lives bringing transparency—uncovering and revealing every hidden condition Using specific figures just as Ms Son Phuong demonstrates the problem asks: What is the average age of these senior monks Now we can easily recall the formula for calculating the average of multiple numbers where the numbers involved here are 3 Lifespan of the three monks And Hidden number Age of the second person The first step in solving is to determine The second person's lifespan The lifespan in years is Take 90 divided by 5 then multiply by 4 or alternatively multiply 90 by 4 over 5—either way you'll get 72 years old At this point we will calculate the average Add the ages of the three senior monks The average lifespan we will obtain is The sum of the lifespans of the three individuals This is for three When searching at 87 years old this is precisely The lifespan of revered monks So that we may We'll keep it set up so we can do the other exercises Then we'll move on to The next one The average of Tung and Son's math test scores is a number that comes immediately before the largest one-digit number In this problem we see that the given information tells us that the average represents the math score of the two students That is when the average is calculated it reflects the combined math score of the two students Conditions for the emergence of conditions Indicates that the average is the memory The average of two numbers is Take the first number Take the first number which is your score Tung add Son's score then divide by 2 the result is the number immediately before it The largest single -digit number is 8 So then we will use the formula for finding the average number which involves finding the sum The total score of Tùng and Sơn — that's what we' ll have giving us the combined total of both students ' scores and once we have that The combined score of these two students Let's continue reading The next requirement of the problem The problem's condition Math score Tung's score is 10 That's it Calculate Son's math score Tung's math score is specifically 10 already And condition 1 we have That's how we find the total score of the two students when we know the average and today we' ll easily recognize it right away We're looking for Tùng 's math score knowing the total won't help us directly We'll take the total and subtract it from Tùng's score to find your friend Sơn's math score That's right isn't it my children That's it Then we Remember to remind This is exactly the steps Miss Son wanted Written here so the child can remember How to visualize what connects to what The math of life And this problem Ms Son also wants To share with her students Why are these two friends Tung and Son Having math scores that differ so greatly that's the truth my child That's exactly it—when my math score is low there are numerous possible reasons one being that I wasn't careful enough while doing the problems I wasn't focused during my studies but I managed to figure out the solution method so when I entered the exam room the answers came easily Feeling very unsure so to gain confidence when taking tests remember to stay focused throughout your math studies We focus on learning so we can grasp the methods for solving original problems and their extensions enabling us to practice extensively and master them as skills We can excel in the test just like Tung did and through this exercise Ms Son also wants to remind you that when we When given the condition To find the arithmetic mean Or to determine the average value Then we can calculate The total hidden within that average If the average of two numbers is known we can find their sum if the average of three numbers is known And we connect to the following conditions So we can find the solution to the problem And this is precisely the dimension of this problem And now we'll begin solving the problem Next we'll find the largest number immediately following the largest bound The largest one-digit number is 8 So the total score of the two students is 8 × 2 × 16 And now we can easily use How to find the lower number for a given sum To determine your friend Son's score That's 16 times 10 times 6 points And here is the number of problems Moving on to the next problem A relief truck is waiting for a team Acting as a student step into this math problem upon reading this question and we are now recognizing the image of a convoy of vehicles Doing good deeds Delivering supplies to aid flood-affected communities Two trucks Each truck carries two tons Five hundred kilograms of rice Remember this When you reach this condition That's why we must remember 3rd grade math problems Problems involving proportional reasoning When we see that There are 2 vehicles and we know how much each vehicle Then we must determine the total weight of the cargo in metric tons or in kilograms Two trucks have already carried it under these conditions we can easily convert this 2 tons and 5 quintals of rice into kilograms And we will multiply 2 We will find the total number of rows Of the 2 vehicles Initially carrying Then continue with the 3 following vehicles Can carry 6 450 kg of rice So now By this sentence we see that This 6 450 kg of rice It is a specific figure—representing the total amount of rice carried by the three following vehicles The problem asks for the average load per vehicle How many kilograms does each vehicle carry This is when the students need to think critically Remember the general formula For the type of problem finding the average of several numbers we simply add all the numbers together and divide by the count of numbers Comparing this problem we see there are five participants namely the five cars—two at the front and three at the back That's right and we need to calculate the total number of bags the total amount of rice the combined load carried by all five trucks and then determine the average Each vehicle's aspect and through that recent line of thought we can easily calm our minds and find the essence of the problem right my dear students This is precisely the thinking process that Ms Xuan just outlined: we begin by converting 2 tons and 5 quintals Xa kg Exchanging 2 tons equals 2 000 kg 5 quintals equals 500 kg Then we will begin Calculating the rice capacity Carried by the first two trucks Specifically Take one truck Multiply the weight of one truck by 2 We obtain the total weight of rice in the first two trucks Then we will Apply the formula To calculate the average value I'll take the total amount of rice from the first two trucks add it to the total from the next three trucks and then divide by the five trucks participating And thus the result of the problem is Exactly 2 290 Which is the average amount Each vehicle carries When transporting rice Relief for flood victims Isn't that right Through this exercise we'll once again Reinforce the spirit of mutual care and compassion A beautiful trait of the Vietnamese people one we remember and strive to learn from as they say And so after today's lesson we've explored math problems —from basic to advanced at level 2 In the lesson on finding average numbers the teacher will help students explore more advanced problems in the next class Level 3 and Level 4 on average numbers And here it is The exercises That Ms Xuan wants you to take home Practice enables us to complete the solution Mastering the skill To solve the average calculation problem Teacher Xuan quickly shares Students who acquire A solid grasp of The content of each question type That's it our lesson is over now See you and goodbye dear students Until our next class