It's a Try

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Purpose

This is a level 4 number link activity from the Figure It Out series. It relates to Stage 7 of the Number Framework.

A PDF of the student activity is included. 

Achievement Objectives
NA4-2: Understand addition and subtraction of fractions, decimals, and integers.
Student Activity

Click on the image to enlarge it. Click again to close. Download PDF (196 KB)

Specific Learning Outcomes

add and subtract integers

Required Resource Materials

FIO, Link, Number, Book Four, It's a Try, page 8

Activity

This very practical application and context introduces students to working with integers. The students will have varying degrees of skill in terms of addition and subtraction. Most should have some experience with using number lines with games and studying such things as temperatures, sea levels, bank balances, and so on. The development of mental fluency is made more difficult because it is often difficult to set up realistic situations that produce negative results, for example, 3 – 7 cannot be easily represented directly by physical objects.
Some important basic principles of number lines include:

• The set of integers includes zero, with positive and negative integers spaced evenly on the number line to the left and right of (or above and below) the zero.

• Adding a positive integer is represented by movement to the right on the number line. Adding a negative integer is represented by movement to the left.

• Subtracting a positive integer is represented by a movement to the left and subtracting a negative integer by movement to the right.

Begin the activity with class discussion to make sure that the mathematical information is well understood. The students could work through questions 1a and 1b in pairs before again sharing their understanding and answers with the class.

You need to prompt the students’ understanding with questions such as:
“What happens when a positive number is subtracted from a positive number?”
“What happens when a positive number is subtracted from a negative number?”
A table of progress will help the students to keep track of each stage. For example:

table.
You could encourage your students to support their findings with a number line.
For example, for 8 – 18 = -10:

line.
Using the additive (reverse) method of subtraction would help the students to solve question 1c. Ask the students to find the two numbers -25 and -48 on the number line and count or add the difference between them. In this case, the students need to find out the distance from -25 to -48 in the negative direction.
number line.
The students could extend this practice context for integers by creating their own bank balance stories using black and red balances, deposits, and withdrawals.

Answers to Activities

1. a. -0:00:10
b. -0:00:25
c. 23 s
d. -0:00:43
2. a. 34 s
b. 0:00:14
3. -0:00:57

Attachments
ItsATry.pdf195.99 KB
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Level Four