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Counting and writing to 20
Joyful Mathematics: Chapter 4
GoalGroup things into a ten and some ones, and write the number.
New words
tens and ones · a group of ten and the things left overgroup of ten · ten things put togetherwrite · show the number in figures
Explanation
To count many things, make a group of ten first. Count the things that are left over. Say the ten and the ones together. A group of ten and 4 more is 14. A group of ten and 7 more is 17. Now we write the number: 14 or 17.
Worked examples
A group of ten and 3 more. There are 13.
A group of ten and 6 more. There are 16.
Here is a row of numbers from 11 to 20. A number is missing: 14.
Class activity
Pack the tens. Pour out some buttons or seeds, not more than 20. Make one pile of exactly ten. Count the ones that are left. Say the number: ten and 6 is sixteen. Write it on paper. Then mix them up and try with a new handful.
Practice
1
Count and write the number. Make a group of ten first.
17.
2
Count and write the number.
19.
3
Find the hidden numbers.
13 and 17.
4
A group of ten and 8 more. What is the number?
18.
5
Write the number that comes just after 11.
12.