This is a level 2 number strand activity from the Figure It Out series.
A PDF of the student activity is included.
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solve problems using additive strategies
You will need to clarify the terms “withdrawal” (removing money from the account), “deposit” (putting money in), and “balance” (the amount of money in the account).
Students can answer question 1 in a variety of ways. It is vital that students record and explain their reasoning: “Twelve weeks is 2 more weeks. That’s another $4.”
“Twenty-four weeks is 12 x 2. Twelve weeks was $24, so I multiplied that by two.”
With question 2, which is expressed in words, encourage students to make sense of the problems before trying to solve them. Use questions such as:
“What is the question asking you to do?”
“Can you find the important information you need to solve this problem?”
“What is a likely answer to this problem?” (to encourage students to estimate)
Question 2b involves finding the difference between the $56 Ani has saved and the $70 she needs. This may be done by adding on or subtracting:
Students will need to organise their calculations in order to find a solution. They may find a table helpful. For example:
Various scenarios can be used, such as, “If Ràwhiti saved $5 each week, who would be the first person to buy their skates?”
A computer spreadsheet could be used to solve the problem. Again, this would be set up in a table:
Question 2 requires students to think carefully about the information on the table and the weeks involved. A useful strategy would be to repeat the table with the changed information inserted.
Answers to Activity
1. a. $24
2. a. 33 weeks (Before she withdrew the $10, her balance was $66.)
b. $14 ($70 – $56 = $14)
1. Tyrone (He would have $42 after 14 weeks, Kelly would have $40 after 15 weeks, and Ràwhiti would have $40 after 20 weeks.)
2. Yes. He spends $3 on the present that week, but over the following 2 weeks, he would save another $6, which would give him $42.