Grade 1 (age 6-7)

grade 1 Numbers up to 50

Counting to Fifty

When there are many things, counting one by one gets hard, so grouping them in tens is much faster. Twenty-three is two tens plus three ones, where the number of groups is the tens digit and the leftovers are the ones digit. That is how a two-digit number is built from tens and ones. You can also skip-count ten, twenty, thirty to move through big numbers fast. Change the tens and ones with the sliders and watch the skip-counting pattern on the number line.

Let's Group by 10!

📦 Why Group by 10?

①It's hard to count many candies at once

②Grouping by 10 makes it fast!

③Two tens = 20, three tens = 30

Counting in Tens

Total Count23

💡 Tens and Ones

①Yellow dashed groups have 10 each

②Blue blocks are leftover ones

③23 = 2 tens + 3 ones

④The groups are the tens place; leftovers are the ones place

⑤Try changing the slider!

Skip-Counting by 10

Skip Count30up to

🦘 Hop by 10!

①10, 20, 30, 40, 50 — grows by 10

②This is called "skip-counting"

③30 + 10 = ? → 40!

④Skip-count up to 50

Summary

Group by 10

tens + ones = total

Grouping by 10 makes counting fast

Skip-count by 10

10 → 20 → 30 → 40 → 50

Each step adds 10

🎯 Remember!

①Grouping by 10 makes counting easy

②How many tens? + How many ones?

③Skip-counting helps with big numbers

④35 = 3 tens + 5 ones. The same rule works for 23 or 42

⑤Great job! Ready for 100?

Examples and Unit Test

Example 1

There are 3 tens and 5 ones. How many are there in all?

Three tens make 30.

Adding the 5 ones gives 30 + 5 = 35.

▸ 35

The number of tens is the tens digit; the number of ones is the ones digit.

Example 2

How many tens and how many ones make up 42?

The tens digit of 42 is 4, so there are 4 tens.

The ones digit of 42 is 2, so there are 2 ones.

▸ 4 tens and 2 ones

A two-digit number splits into (tens digit) tens and (ones digit) ones.

Unit Test

What number is made of 2 tens and 7 ones?

①17

②27

③72

④20

▸ ② 27

Two tens make 20.

Adding 7 ones to 20 gives 27.

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Numbers up to 9

Numbers up to 100