4
Estimate, then count
Learner’s Book 1: Unit 9, pp. 129–131
GoalMake a sensible estimate (fewer than 10, or between 10 and 20) and then count to check.
New words
estimate · a good guess about how manybetween · in the middle of two numberscheck · count to see if you were right
Explanation
An estimate is a good guess. Look at the things quickly and decide: is there a small group, fewer than 10, or a bigger group, between 10 and 20? Then count carefully to check. Your estimate does not need to be exactly right, but it should be close. The more you practise, the better your estimates will be. Estimating helps us to know if an answer makes sense.
Worked examples
It looks like a small group, fewer than 10. Count: 1, 2, 3, 4, 5, 6. There are 6.
It looks like a big group, between 10 and 20. Count 10, then on: 11, 12, 13, 14, 15. There are 15.
Ali estimates 10 beads. He counts 12. His estimate is close.
Class activity
Guess jar: put 12 to 18 small things in a jar. Say your estimate first: fewer than 10 or between 10 and 20? Write a number. Then count to check, using a full ten and then counting on. Who was closest?
Practice
1
Estimate: fewer than 10 or between 10 and 20? Then count.
fewer than 10; 8
2
Estimate: fewer than 10 or between 10 and 20? Then count.
between 10 and 20; 17
3
Nodira estimated 15. The count was 16. Was her estimate close?
Yes, 15 is very close to 16.
4
Why do we estimate first and then count?
To get better at knowing how many, and to check our count.