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Review: numbers to 20 and patterns
Learner’s Book 1: Unit 9, pp. 118–136
GoalRead and compare numbers to 20, see a teen number as a ten and some ones, and use odd and even numbers, twos and tens.
New words
teen number · a number from 11 to 19, made of a ten and some onesgreater · more thanodd and even · even numbers make pairs with none left over; odd numbers have one left over
Explanation
Numbers from 11 to 19 are made of a ten and some ones. 13 is 10 and 3. 20 is two tens. To compare two numbers, the one that comes later on the number line is greater. 17 is greater than 12. We can count in twos: 12, 14, 16, 18, 20. These are even numbers. Odd numbers are 1, 3, 5, and so on. Ten more is one row down the number track, and ten fewer is one row up.
Worked examples
19 is 10 and 9. A full ten frame and 9 more make 19.
17 is greater than 12 because it is further along the number line. 12 is less than 17.
Count in twos from 12: 12, 14, 16, 18, 20. Each is 2 more. All of them are even.
Class activity
Number cards: make cards 1 to 20. Pick two and say which is greater and which is less. Pick one card and say two more, two fewer, ten more or ten fewer (if you can). Put the even cards in one pile and the odd cards in another.
Practice
1
How many are shown in the ten frames?
16
2
Which number is less, 13 or 19?
13
3
Write the number word for 18.
eighteen
4
Count in twos: 3, 5, 7, __, 11. Which number is missing?
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