Learning Objectives
- Count objects from 10 to 20
- Read and write numbers from 10 to 20
- Understand that numbers after 9 have two digits
- Know the order of numbers from 10 to 20
- Compare numbers between 10 and 20
Key Concepts
The Number Ten
Ten is a special number. It is the first number with two digits. We write it as 10. Ten means one group of ten things. When we count 10 fingers, we use all the fingers on both our hands. After 9 comes 10.
Numbers 11 to 20
After 10, we count 11, 12, 13, 14, 15, 16, 17, 18, 19, 20. The number 11 means ten and one more. The number 12 means ten and two more. This goes on: 13 is ten and three, 14 is ten and four, 15 is ten and five, 16 is ten and six, 17 is ten and seven, 18 is ten and eight, 19 is ten and nine, and 20 is two groups of ten.
Tens and Ones
Every two-digit number is made of tens and ones. The number 14 has 1 ten and 4 ones. The number 18 has 1 ten and 8 ones. The number 20 has 2 tens and 0 ones. This is the beginning of understanding place value.
Counting and Comparing
To compare numbers from 10 to 20, look at them on a number line. A number that comes later is bigger. So 15 is bigger than 12, and 20 is bigger than 17. We can also use words like greater than and less than.
Important Terms
- Two-digit number: A number that has two digits, like 10, 14, or 20
- Tens: Groups of ten objects
- Ones: Single objects left over after making groups of ten
- Place value: The value of a digit based on its position
- Twenty: The number 20, which is two groups of ten
Quick Revision
- 10 is the first two-digit number
- Numbers from 11 to 19 all have 1 ten and some ones
- 20 has 2 tens and 0 ones
- After 9, numbers have two digits
- We can break any number from 10 to 20 into tens and ones
- Practice counting from 10 to 20 forward and backward