2
Find the missing number
Learner’s Book 1: Unit 1, p. 20
GoalFind a number that is missing from the number track by saying the numbers in order.
New words
missing · not there; you need to find itbetween · in the middle of two numbersnumber track · a row of numbers from 1 to 10, in order
Explanation
Sometimes a number is hiding. Look at the track: 1, 2, ?, 4. What goes in the gap? Say the numbers from the start: 1, 2 and then 4. The number we skipped is 3. The number between 2 and 4 is 3. If you forget, say the rhyme quietly in your head. Look at the number before the gap and the number after it.
Worked examples
Which number is missing? Say 1, 2, 3, 4, 5 and then we see 7. We skipped 6, so 6 is missing.
Two numbers can be missing. Say 1, 2 and then 5. We skipped 3 and 4. They are the missing numbers.
What is between 7 and 9? Say 7, 8, 9. The number between is 8.
Class activity
Hide the number: lay cards 1 to 10 in order. Close your eyes while your partner takes one card away. Open your eyes and say which number is missing. Then take turns. Later, take two cards away.
Practice
1
Which number is missing?
7
2
Write the missing numbers.
2 and 6
3
What number is between 4 and 6?
5
4
A track shows 1, 2, 3, 4, 5, 6, 7, 8, 9 and then an empty box. Which number goes in the box?
10