## Magical tens

This is a level 2 number activity from the Figure It Out series. It is focused on using additive strategies (make a ten) to solve addition problems. A PDF of the student activity is included.

## About this resource

*Figure It Out* is a series of 80 books published between 1999 and 2009 to support teaching and learning in New Zealand classrooms.

This resource provides the teachers' notes and answers for one activity from the* Figure It Out* series. A printable PDF of the student activity can be downloaded from the materials that come with this resource.

Specific learning outcomes:

- Use additive strategies (make a ten) to solve addition problems.

# Magical tens

## Achievement objectives

NA2-1: Use simple additive strategies with whole numbers and fractions.

## Required materials

*Figure It Out, Levels 3-4, Basic Facts*, "Magical tens", page 11- counters
- photocopy of
*Magical tens CM*board - a classmate

See **Materials that come with this resource** to download:

*Magical tens activity*(.pdf)*Magical tens CM*(.pdf)

## Activity

This activity will help students to bridge through 10 or a multiple of 10 as a mental strategy for addition. Initially, a Make Tens board is used as a model. Students are then encouraged to visualise the process, and finally, to work with numbers in their mind only.

Using the *Make Tens CM* board as a model for the calculation 8 + 7, it is useful to see the 7 as 5 + 2, taking the 8 up to 10, and then adding the remaining 5. To help the students split the numbers, you could ask questions like:

- What do you need to add to 87 to make the next multiple of 10? or
- What two parts will you break the 6 into?

Using these models and activities, the students should see how useful part-whole thinking is.

The students can use a *Make Tens* board to check their answers to question 3.

Another good model for the same strategy is a number line. Encourage the students to visualise from this model using the same process.

For example:

*Magical Tens* is complemented by the activity on page 14 of the student booklet, which uses subtraction.

**1.**

a. 18 + 7 = 25

b. 28 + 7 = 35

c. 38 + 7 = 45

**2. **

Discussion may vary, but the statements on the boards could be written as:

a. 9 + 6 = 10 + 5 = 15

b. 7 + 6 = 10 + 3 = 13

c. 9 + 8 = 10 + 7 = 17

d. 8 + 7 = 10 + 5 = 15

**3.**

a. 20 + 5

b. 30 + 5

c. 60 + 5

d. 90 + 5

e. 30 + 3

f. 50 + 3

g. 80 + 3

h. 90 + 3

**4.**

a. 19 + 8 = 20 + 7 = 27

b. 59 + 8 = 60 + 7 = 67

c. 109 + 8 = 110 + 7 = 117

d. 1 009 + 8 = 1 010 + 7 = 1 017

e. 47 + 6 = 50 + 3 = 53

f. 67 + 6 = 70 + 3 = 73

g. 237 + 6 = 240 + 3 = 243

h. 997 + 6 = 1 000 + 3 = 1 003

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