Part 1 — Lessons (23)
1. Tens and Ones
A two-digit number is made of tens and ones. In 34, the 3 means 3 tens (30) and the 4 means 4 ones.
So 34 = 30 + 4.
Try this: How many tens are in 50? (5 tens.)
2. Skip Counting, Even and Odd
Skip counting means counting in steps: by 2s (2, 4, 6, 8) or by 5s (5, 10, 15, 20).
Even numbers can be shared into two equal groups (2, 4, 6). Odd numbers cannot (1, 3, 5, 7).
Try this: Is 8 even or odd? (Even.)
3. Skip Counting
Skip counting is counting in jumps instead of by ones.
By 2s: 2, 4, 6, 8, 10. By 5s: 5, 10, 15, 20. By 10s: 10, 20, 30, 40.
Skip counting helps you count fast and gets you ready for times tables.
Try this: Count by 5s up to 30. (5, 10, 15, 20, 25, 30.)
4. Adding Bigger Numbers
To add two-digit numbers, add the ones first, then the tens.
For 25 + 13: ones 5 + 3 = 8, tens 20 + 10 = 30, so the answer is 38.
Line the numbers up so ones are under ones and tens under tens.
Try this: What is 12 + 7? (19.)
5. Telling Time on a Clock
A clock has two hands. The short hand shows the hour; the long hand shows the minutes.
When the long hand points to 12, it is an o’clock time. If the short hand points to 3 and the long hand to 12, it is 3 o’clock.
When the long hand points to 6, it is half past the hour.
Try this: Short hand on 9, long hand on 12 — what time is it? (9 o’clock.)