1
Counting on in ones
Learner’s Book 1: Unit 13, pp. 180–181
GoalAdd by counting on in ones along a number line.
New words
count on · start at a number and say the next numbers in ordernumber line · a line with numbers in orderjump · one hop along the number linetotal · how many altogether
Explanation
Sometimes we have some things and then we get more. To find the new total we count on. Start at the first number and count on the second number, one at a time. On a number line we draw a small jump for every number we say. To add 8 + 5, start at 8. Count on 5: 9, 10, 11, 12, 13. The jumps end at 13, so 8 + 5 = 13.
Worked examples
Sara has 12 stickers and gets 3 more. Start at 12 and count on: 13, 14, 15. So 12 + 3 = 15.
To add 15 + 4, start at 15 and count on: 16, 17, 18, 19. So 15 + 4 = 19.
Mia has 10 shells in a box and puts 2 more in. Start at 10 and count on: 11, 12. The total is 12. It is quicker than counting every shell again.
Class activity
Hopping line: draw a number line from 0 to 20 on the ground with chalk, or use paper with big numbers. Choose a start number up to 14. Roll a dice and hop forward that many steps, saying each number. Where do you land? Say the sum.
Practice
1
What is 10 + 4? Start at 10 and count on in ones.
14
2
What is 6 + 5? Start at 6 and count on in ones.
11
3
What is 14 + 3? Count on from 14.
17
4
Zara has 11 beads and finds 5 more. How many beads does she have now?
16 beads (11 + 5)