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Nineteen and twenty
Discover Mathematics: Chapter 4
GoalCount, read and write 19 and 20, and show twenty as two tens.
New words
nineteen · ten and nine moretwenty · two tensfull · with no empty square
Explanation
Nineteen is ten and nine more. On two ten-frames it is one full frame and nine counters, with just one square empty. After nineteen comes twenty. Twenty is two full ten-frames, so twenty is two tens: ten and ten more. The numeral 19 is a 1 followed by a 9. The numeral 20 is a 2 followed by a 0. Twenty is the biggest number we count in this chapter.
Worked examples
Twenty is two full ten-frames. Ten and ten more make twenty.
Mariam and Hana each have 10 stickers. Together they have 20 stickers.
Count all your fingers and toes: 10 fingers and 10 toes make 20.
Class activity
Count to twenty. March around the room and count each step up to 20. Then clap on every number from 15 to 20. Finally, stand still and count backward from 20 to 15 in a whisper.
Practice
1
How many cherries are there?
19
2
How many hearts are there?
20
3
Say the numbers from eighteen to twenty out loud: 18, 19, 20.
18, 19, 20
4
What is ten and ten more?
20
5
What is one less than 20?
19