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Review: length, adding and taking away
Learner’s Book 1: Units 4–5, pp. 56–85
GoalCompare lengths, add two groups, take some away and use number bonds to 10.
New words
longest · the most long of alladd · put two groups togethertake away · remove some from a groupnumber bond · two numbers that add to make a total
Explanation
To compare lengths, line things up at the same start. The one that goes furthest is the longest, and the one that stops first is the shortest. For a tower, the highest one is the tallest. To add, put two groups together and count how many altogether: 4 + 3 = 7. To take away, cross out some and count what is left: 7 − 5 = 2. Two numbers that add up to a total are a number bond for it, like 6 + 4 = 10. Number bonds help you add and take away.
Worked examples
Ribbon A goes the furthest, so it is the longest. Ribbon C stops first, so it is the shortest.
4 cherries and 3 cherries are 7 cherries altogether. 4 + 3 = 7.
There are 7 apples. Take away 5. 2 are left. 7 − 5 = 2.
Class activity
Mixed-up game: use 10 buttons. Make two groups and add them. Then take some away and say how many are left. Then line up 3 things from your bag (a pencil, a spoon, a crayon) and find the longest and the shortest. Finally, find as many number bonds for 10 as you can.
Practice
1
Which tower is the tallest?
C (9 blocks)
2
How many stars altogether?
9 (5 + 4 = 9)
3
How many fish are left?
3 (10 − 7 = 3)
4
Complete the number bond: 3 + __ = 10.
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