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Key Point: Next number = current number + 1 (e.g., if n = 37, next = 37 + 1 = 38).
Counting from 21 to 50 means saying all whole numbers beginning with twenty-one and ending with fifty in order. These numbers can be grouped into three tens: 21–30, 31–40 and 41–50. Each number has two parts: the tens place and the ones place. For example, 34 has 3 tens and 4 ones (thirty-four).
How to count: Start at 21 and say the next number by adding one each time: 21, 22, 23, ... up to 50. Notice the spoken pattern: numbers 21–29 start with "twenty-", 30–39 start with "thirty-", 40–49 start with "forty-", and 50 is "fifty." When the ones digit goes from 9 to 0, the tens digit increases by 1 (for example, after 29 comes 30).
Teaching tips: Use objects (blocks, beads, stones) to show each number. Group objects in tens to make the tens place visible. Write the sequence on a number line or chart and ask the child to point to the next or previous number to build confidence.
Key Point: Two-digit number = (tens × 10) + ones, e.g. 34 = (3 × 10) + 4 = 30 + 4.
What are numerals and number names? Numerals are the digits or figures we write to show a number (for example 27). Number names are the words we use to read or write that number in English (for example twenty-seven).
Numbers from twenty-one to fifty are all two-digit numbers made of a tens place and a ones place. For any number from 21 to 50, the first digit tells how many tens and the second digit tells how many ones. Example: 34 has 3 tens and 4 ones, so 34 = 3 tens + 4 ones = 30 + 4.
How to write number names: For numbers 21–99 (except exact tens) we write the tens word, a hyphen, then the ones word. Examples of tens words: twenty, thirty, forty, fifty. So 21 = twenty-one, 30 = thirty, 45 = forty-five. (Note the spelling 'forty' not 'fourty'.)
Teaching tools and methods: Use ten-rods (tens) and unit-cubes (ones) or ten-frames to show tens-and-ones. Use a number line from 20 to 50 for counting forward and backward. Show expanded form (for example 46 = 40 + 6) and practice matching numerals with their number names.
Tips for learners: Always check the tens place first to know how many tens (20, 30, 40, 50) then read the ones. Use objects from daily life (apples, pencils, students) to make counting and naming numbers easy and meaningful.
Key Point: Number = (Tens × 10) + Ones
What is place value? Place value tells us the value of each digit in a number depending on where it is written. For two-digit numbers (21 to 50) there are two places: Tens and Ones.
Tens: The left digit shows how many groups of ten are in the number. Each group of ten equals 10.
Ones: The right digit shows how many single ones are left after making groups of ten.
How to find tens and ones (step-by-step):strong>
Reading and writing: To read 47 say "forty-seven." To write tens and ones: 47 → 4 tens and 7 ones.
Why this helps: Knowing tens and ones makes counting, comparing, and adding simple numbers easier. It shows that the left digit is worth more (each step left multiplies value by 10).
Teaching tips / classroom activities:
Key Point: Number = (Tens × 10) + Ones — e.g., 34 = 3 × 10 + 4
What it means: Representing numbers (21–50) means showing a number in different ways so children understand how many tens and ones make the number. We use numerals (like 34), number words (thirty-four), groups of ten (bundles or sticks), ones (single objects), and a number line to show position.
Key ideas:
How to show a number step-by-step (example: 46):
Why this helps: Using many representations (objects, pictures, words, numerals, and lines) builds a strong number sense so children understand both the size of a number and how it is built from tens and ones.
Key Point: Successor of n = n + 1
What is a number line? A number line is a straight horizontal line that shows numbers in order. On a number line, numbers increase from left to right. For Class 1 (numbers 21 to 50) we draw marks at equal distances and write the numbers 21, 22, 23 ... up to 50.
How to draw it:
Uses of the number line:
Tips for learners: Use small objects (buttons, coins or stickers) to place on the ticks while learning. Colour a group of ten (21–30, 31–40, 41–50) to show tens. Practice hopping for + and - so children see movement on the line.
Key Point: After of n = n + 1
What it means: "Before" means the number that comes just one less than a given number. "After" means the number that comes just one more than a given number. "Between" means the number(s) that come in the middle of two numbers.
How to find:
Using numbers 21 to 50: If you are given a number from 21 to 50, the after and before numbers are close by. Example: after 34 is 35 (34 + 1), before 34 is 33 (34 - 1). If asked for the number between 23 and 25, the number between is 24.
Tips for young learners: Use a number line and move one step forward to get the "after" and one step backward to get the "before." For "between," see which numbers come in the steps between two marks.
Key Point: a > b means a is greater than b
What it means
Comparing numbers means finding which number is smaller, which is bigger, or whether two numbers are equal. Ordering numbers means arranging a group of numbers from smallest to biggest (ascending) or from biggest to smallest (descending). This topic uses numbers from 21 to 50.
Symbols and words
Use > for 'greater than', < for 'less than', and = for 'equal to'. For example: 35 > 30 (read: 35 is greater than 30).
Simple rule using the number line
Put numbers on a number line. The number that is to the right is greater. The number to the left is smaller.
Step-by-step way to compare two numbers (21–50)
Teaching tips
Use real objects (balls, pencils, apples) so children can count and see which pile is bigger. Use the 'alligator mouth' idea: the mouth opens to eat the bigger number (symbol > or <).
Key Point: Number = (Tens × 10) + Ones
What it means: Formation and decomposition of numbers (21–50) means understanding how a two-digit number is made from tens and ones, and how a number can be broken (decomposed) into those parts. Every two-digit number has a tens place and a ones place.
Place value idea: In numbers from 21 to 50 the tens digit can be 2, 3, 4 or 5. For example, 34 has a tens digit 3 and ones digit 4. That means 34 = 3 tens + 4 ones.
How to form a number (step-by-step):
How to decompose a number (step-by-step):
Using objects: Use sticks/strips of ten (bundles) for tens and single counters for ones. To make 31 use 3 bundles of ten and 1 counter. To decompose 45 remove 4 bundles and 5 counters.
Why it helps: Knowing formation and decomposition helps in quick addition, subtraction and in reading or writing numbers correctly.
Key Point: Next term = Previous term + constant difference (e.g., add 1, add 2, add 5).
Patterns and sequences are ways numbers or shapes are arranged so we can see what comes next. In Class 1, using numbers 21 to 50, children learn to spot repeating designs (ABAB), growing lists (21, 22, 23…), and skip-counting (21, 23, 25…).
How to recognize patterns with numbers 21–50:
Finding the next number: look at how the numbers change from one term to the next (add the same amount, subtract the same amount, or repeat a block). Encourage children to say the rule aloud: “add 1”, “add 2”, “subtract 1”, or “repeat colours”.
Key Point: Number = (Tens × 10) + Ones — e.g., 46 = (4 × 10) + 6
What this topic covers
In Class 1, the topic 'Exercises and Activities' for Numbers from Twenty-one to Fifty helps children practise counting, reading, writing and understanding numbers 21–50. Key ideas: ordering numbers, finding missing numbers, tens and ones (bundles and singles), comparing numbers, simple addition/subtraction by 1, and using objects to show numbers.
Suggested classroom activities
How to guide students
Use real objects, visual aids and repeated short activities. Encourage counting aloud, pointing to each object while counting, and showing numbers using tens-bundles and ones. Keep activities playful and short (5–10 minutes each).