Weka Wobble

In this activity, the students record their addition and subtraction methods on a number line. This gives them a visual record of their mental strategies. Using a number line marked in decades (10, 20, 30, …) gives the students some structure for their recording. Later, as they develop a wider range of strategies and greater confidence about number relationships, an empty number line may be more suitable. The students should also be able to discuss and explain their recording.
The students often solve problems that ask “How many more?” by using a missing-addend approach, that is, 63 +  = 100. Some students, though, will think of these as subtraction problems, that is, 100 – 63 = . Their strategy might be “I’ll start from 100 and go back to 60 … that’s 40. Then I’ll go up 3 to 63. 40 take away 3 is 37.”
There are a number of other methods that the students might use when working on an empty number line. These include:

 

Answers to Activity

1. Answers will vary. Teacher to check
2. a. 91 more weka
b. 71 more weka
c. 45 more weka
d. 16 more weka
3a. 20 more robins
b. 69 more robins
c. 118 more robins
d. 96 more robins