Place Value and Numbers to 120: Year 1 Study Guide
Where a digit sits tells its value. In Year 1, children discover that numbers are made of tens and ones.
Year 1 children count forwards and backwards from any number up to 120 and learn that numbers beyond 9 are made of tens and ones. In 36, the 3 stands for 3 tens (30) and the 6 stands for 6 ones. Ten ones make one ten, and ten tens make one hundred.
Bundling matters. Tie ten paddle-pop sticks into a bundle and a pile of 23 becomes 2 bundles and 3 loose sticks. When children handle real materials, symbols like 23 start to mean something.
Partitioning
To partition is to break a number into parts. 36 = 30 + 6. It can also be partitioned in other ways: 36 = 20 + 16 or 36 = 10 + 26, which is useful for mental addition.
| Number | Tens | Ones | Partitioned |
|---|---|---|---|
| 14 | 1 | 4 | 10 + 4 |
| 52 | 5 | 2 | 50 + 2 |
| 90 | 9 | 0 | 90 + 0 |
| 110 | 11 | 0 | 100 + 10 |
Skip counting
Counting by twos (2, 4, 6, 8…), fives (5, 10, 15…) and tens (10, 20, 30…) is quicker than counting by ones and prepares children for multiplication. A hundred chart shows the patterns: the fives end in 0 or 5, and the tens form a column.
Comparing and ordering
To compare, look at the tens first. 64 is greater than 46 because 6 tens is more than 4 tens. Use the words more than, less than and the same as. To order numbers, put them on a number line from smallest to largest.
Which has more?
Which has more?
64 is more than 46.
Worked examples and common mistakes
Example: What is one more than 59? 60. Example: Count backwards from 83 to 78. 83, 82, 81, 80, 79, 78. Common mistakes: mixing up the digits (writing 61 for 16), missing a number at the tens boundary (e.g. 'thirty-nine, thirty-ten') and not seeing that 10 more changes only the tens digit. Use a hundred chart to find the number below or above.
Check your understanding: model answers
1. 40 + 7. 2. 73 is more, because 7 tens is more than 3 tens. 3. 99.
✨ Key Takeaways
- Numbers above 9 are made of tens and ones.
- Partition numbers into parts such as 36 = 30 + 6.
- Skip count by 2s, 5s and 10s.
- Compare the tens first, then the ones.
💬 Questions for Discussion & Reflection
- Partition 47 into tens and ones.
- Which is more, 73 or 37?
- What number comes before 100?