The Shanghai Maths Project Practice Book 5B Sample Unit

Page 1

Chapter 7 Introduction to positive and negative numbers

Unit 7.1 Positive and negative numbers (1) Conceptual context This chapter introduces negative numbers. Negative numbers help to describe values less than zero. Due to their abstract nature, they should be introduced in context. Negative numbers represent opposites. Positive numbers represent values greater than a given benchmark (reference point), while negative numbers represent values less than the benchmark (the benchmark is often zero). If positive represents a movement to the right, negative represents a movement to the left. Pupils will already have met negative numbers in everyday life. They may have seen negative floor numbers in lifts, corresponding to basement floors below ground level. They will be familiar with temperatures expressed as negative numbers. Temperatures above zero are positive while temperatures below zero are negative. Domestic freezers are generally set to −18 °C and the fridge temperature varies between 3 and 5 °C. There is often a live display of these values on a control panel.

i

Positive numbers are usually written without a ‘+’. The + is implied. Thus, positive ten (or ‘plus ten’) can be written as +10 or, more commonly, simply as 10. Negative numbers are always written with a − sign, thus negative ten (or ‘minus ten’) is written as −10.

Learning pupils will have achieved at the end of the unit ●

Temperatures below 0 °C will have been read as negative numbers (Q1, Q5)

Pupils will have practised reading positive and negative numbers (Q2, Q3, Q4, Q5, Q6)

The concept that positive and negative numbers are opposites will have been explored (Q2, Q3, Q4, Q6)

Pupils will have learned that negative numbers must always have − in front of the number (Q2, Q3, Q4)

The understanding will have been established that positive numbers may be prefaced by + but if there is no + it is inferred (Q2, Q3, Q4)

Pupils will have developed and extended their knowledge and understanding of specific, well-known temperatures (Q5)

Pupils will have consolidated their understanding that on the Celsius scale temperatures below zero (the freezing point of water) are represented by negative numbers (Q5)

The concept of a benchmark (reference point) where numbers greater than the benchmark are positive and numbers less than the benchmark are negative will have been introduced (Q6)

50

6968_Shanghai_Maths_TG_5B.indb 50

15/05/2018 09:39


Turn static files into dynamic content formats.

Create a flipbook
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.
The Shanghai Maths Project Practice Book 5B Sample Unit by Collins - Issuu