Lessons with English subtitles
Lessons from Japanese elementary school. You hear the explanation in Japanese, and read the subtitles and the text in English.
The narration and the pictures are in Japanese. You can hear the same words that are used in class at a Japanese school.
Grade 3 Math
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Adding and Subtracting 3- and 4-Digit NumbersUse the column method, no matter how many times you carry or borrow
To add and subtract 3-digit and 4-digit numbers, we use the same idea as the column method for 2-digit numbers: line up the places and calculate in order, starting from the ones place.
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Mental Math with 2-Digit NumbersSplit by place, or make a friendly number
We add and subtract 2-digit numbers in our head, without writing the column method. We use two ideas: splitting the numbers by place, and making a friendly number.
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Finding Times and Amounts of TimeThe time ... minutes later, how long it took, and seconds
We think about "What time is it ... minutes later?" and "How many minutes did it take?" by looking at how the long hand of the clock moves. If you split it at the o'clock time, it is easy to find.
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Big Numbers (Ten Thousands and More)Places, reading, and size of numbers bigger than ten thousand
Numbers bigger than ten thousand have the ten-thousands place, the hundred-thousands place, the millions place, and the ten-millions place. Let's see how to read big numbers by splitting them into groups of 4 digits from the ones place (the Japanese way), how to show their size with a number line and inequality signs, and how numbers change when you multiply them by 10 or divide them by 10.
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DivisionCalculating to share equally
Division is the calculation we use when we share blocks equally. Let's learn how to write a division math sentence and how to check it with multiplication.
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Division, Subtraction, and MultiplicationHow many times you can subtract, and where the □ goes
You can also find the answer to 12 ÷ 3 by finding how many times you can subtract 3 from 12. If you think with a multiplication math sentence that uses □, you can also see that the □ goes in a different place depending on whether you find the number of groups or the number in one group.
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Division with RemaindersRemainders, smaller than the divisor, checking, and what to do with the remainder
When you share things out in equal groups, some may be left over. What is left over is called the "remainder." Let's see how to write a division math sentence with a remainder, how to find the answer with the times tables, how to check it, and what to do with the remainder.
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Bar GraphsShow how big numbers are with the length of bars
A graph that shows the numbers you found with the length of bars is called a bar graph. You can see at a glance which is the most.
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One Division on a Bar GraphRead graphs where one division is 2, 5, or 50, and choose the scale
One division on a bar graph is not always 1. With graphs where one division is 2, 5, 50, and so on, we learn how to find how much one division is and how to read the top of a bar. We also think about choosing the scale to fit the size of the numbers and the size of the paper.
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Combining Tables into OnePut monthly tables together, and read them across and down
We put 3 tables, for April, May, and June, together into 1 table. Reading across shows how the numbers change from month to month, and reading down shows the differences between kinds in the same month. We also use the total row and column to check that the numbers add up.
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Combined Bar GraphsPut two graphs into one, and compare the classes
We combine the bar graphs of favorite games for Class 1 and Class 2 into one graph. The bars for the same game stand next to each other, so it is easier to read the differences between the classes and which games are popular in both classes.
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Multiplication in ColumnsCarrying, and how to write with the places shifted
In the column method for multiplying a 2-digit number by a 1-digit number, you calculate with the times tables starting from the ones place, and add the carried number to the tens place.
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Multiplying by 2-Digit Numbers in ColumnsCarrying, and writing shifted over
In the column method where the number you multiply by has 2 digits, you multiply by the ones digit and the tens digit separately, then add the two answers with the places shifted.
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Estimating the AnswerCalculate with rough numbers, and notice mistakes
You can check whether the answer from the column method is right by estimating with rough numbers. Let's see how to estimate with examples of addition and multiplication.
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Long Lengths (km and Distance Along a Road)Tape measures, kilometers, distance along a road, and straight-line distance
We measure long things and round things with a tape measure. Even longer lengths are shown in kilometers (km). Let's also see the difference between "distance along a road" (michinori), measured along the road, and "straight-line distance" (kyori), measured in a straight line.
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Circles and SpheresCenter, radius, and diameter
A round shape drawn with a compass is called a circle. Let's learn about the center, radius, and diameter of a circle, and about spheres, which are shaped like a ball.
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DecimalsNumbers that show a leftover amount of liquid
When you measure with a 1 L measuring box, there may be a leftover amount less than 1 L. If you use one of the 10 equal parts of 1 L, you can show the leftover amount with a number.
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Adding and Subtracting DecimalsThe column method with carrying and borrowing
If you think about how many 0.1s there are, or line up the decimal points in the column method, you can add and subtract decimals. Let's also look at calculations with carrying and borrowing.
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Units of WeightGrams and kilograms
We weigh things with a scale and show the weight in grams (g) or kilograms (kg). Let's choose the unit that fits what we weigh.
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FractionsShow the size of equal parts with fractions
When you split 1 m into parts of the same length, the length of one part is shown with a fraction. A fraction can also be shown as how many of a base fraction it is.
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Adding and Subtracting FractionsCalculating fractions with the same denominator
For fractions with the same denominator, you can add and subtract by thinking about how many base fractions they are made of. Let's look at cases where the answer is up to 1.
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0.1 and One TenthLine them up above and below the same number line
On a number line where 0 to 1 is split into 10 parts, we write decimals above and fractions below. Numbers that point to the same spot above and below, like 0.1 and one tenth, or 0.7 and seven tenths, are the same size.
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Isosceles and Equilateral TrianglesPay attention to the length of the sides
When you compare the lengths of the sides of triangles, there are triangles with two sides of equal length, and triangles with all three sides of equal length.
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AnglesCompare their size by putting them on top of each other
The shape made by 2 sides coming out from one vertex is called an angle. You can compare the size of angles by putting them on top of each other. We fold isosceles triangles and equilateral triangles to check that their angles are the same size.
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Math Sentences with □Make the unknown number a □, and write the math sentence in the order of the story
Even in a story with a number you don't know, if you make that number a □, you can write the math sentence in the same order as the story. Let's try putting numbers in the □ to check, and finding the □ by looking at a diagram. We try it with addition, subtraction, multiplication, and division stories.
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The Abacus (Soroban)How to move the beads and show numbers
The soroban is a Japanese abacus, a tool that shows numbers by moving beads. We learn what the five-bead and the one-beads mean, how the places work, how to show decimals, and how to move the beads for simple addition and subtraction.
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How Units of Length, Weight, and Volume Are RelatedConnect kilo, centi, milli, and deci
Units of length, weight, and volume have letters in front of them, like "kilo" and "milli." What these letters mean is the same for every unit. Let's find the rules and connect the units.
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How to Use a CompassDraw circles, copy lengths, and draw patterns
A compass is a tool for drawing circles and copying lengths. Let's look, step by step, at how to hold it, open it, and turn it.
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Division Word ProblemsDraw a diagram, then write a math sentence
Let's think about division word problems by drawing a tape diagram. If you find "the total" and "the number in one group," you can write the math sentence.
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Reading a ScaleFind out how much one division is, then read the weight
Read the mark that the scale's pointer points to, and find out the weight. You will learn how to find how much one division is, what to be careful about when you read it, and how to choose a scale that fits what you are weighing.
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Rules of Multiplication and Multiplying by 0Splitting to calculate, and multiplying by 0 and 10
Multiplication has rules: the answer stays the same if you switch the numbers, or if you split a number and calculate. Using these rules, you can also think about multiplying by 0 and by 10.
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Multiplying Tens and HundredsThink in groups of 10 and 100
For multiplication like 20 × 4 and 200 × 4, if you think about how many 10s or 100s there are, you can calculate with the times tables.
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Division with 2-Digit AnswersThink with bundles of 10, and split by place
We think about divisions whose answers have 2 digits, like 60 ÷ 3 and 69 ÷ 3. If you think with bundles of 10, or split the number into the bundles of 10 and the loose ones, you can calculate with the times tables.
More lessons will be added little by little.