NSW Syllabuses

# Mathematics K–10 - Stage 2 - Measurement and Geometry Mass

## Mass 1

### Outcomes

#### A student:

• MA2-1WM

uses appropriate terminology to describe, and symbols to represent, mathematical ideas

• MA2-3WM

checks the accuracy of a statement and explains the reasoning used

• MA2-12MG

measures, records, compares and estimates the masses of objects using kilograms and grams

### Content

• Students:
• Measure, order and compare objects using familiar metric units of mass (ACMMG061)
• recognise the need for a formal unit to measure mass
• use the kilogram as a unit to measure mass, using a pan balance
• associate kilogram measures with familiar objects, eg a standard pack of flour has a mass of 1 kg, a litre of milk has a mass of approximately 1 kg (Reasoning)
• recognise that objects with a mass of one kilogram can be a variety of shapes and sizes (Reasoning)
• record masses using the abbreviation for kilograms (kg)
• use hefting to identify objects that have a mass of 'more than', 'less than' and 'about the same as' one kilogram
• discuss strategies used to estimate mass, eg by referring to a known mass (Communicating, Problem Solving)
• compare and order two or more objects by mass measured to the nearest kilogram
• estimate the number of similar objects that have a total mass of one kilogram and check by measuring
• explain why two students may obtain different measures for the same mass (Communicating, Reasoning)

### Background Information

In Stage 2, students should appreciate that formal units allow for easier and more accurate communication of measures. Students are introduced to the kilogram and gram. They should develop an understanding of the size of these units, and use them to measure and estimate.

### Language

Students should be able to communicate using the following language: mass, more than, less than, about the same as, pan balance, (level) balance, measure, estimate, kilogram.

'Hefting' is testing the weight of an object by lifting and balancing it. Where possible, students can compare the weights of two objects by using their bodies to balance each object, eg holding one object in each hand.

As the terms 'weigh' and 'weight' are common in everyday usage, they can be accepted in student language should they arise. Weight is a force that changes with gravity, while mass remains constant.

## Mass 2

### Outcomes

#### A student:

• MA2-1WM

uses appropriate terminology to describe, and symbols to represent, mathematical ideas

• MA2-2WM

selects and uses appropriate mental or written strategies, or technology, to solve problems

• MA2-12MG

measures, records, compares and estimates the masses of objects using kilograms and grams

### Content

• Students:
• Use scaled instruments to measure and compare masses (ACMMG084)
• recognise the need for a formal unit smaller than the kilogram
• recognise that there are 1000 grams in one kilogram, ie 1000 grams = 1 kilogram
• use the gram as a unit to measure mass, using a scaled instrument
• associate gram measures with familiar objects, eg a standard egg has a mass of about 60 grams (Reasoning)
• record masses using the abbreviation for grams (g)
• compare two or more objects by mass measured in kilograms and grams, using a set of scales
• interpret statements, and discuss the use of kilograms and grams, on commercial packaging (Communicating, Problem Solving)
• interpret commonly used fractions of a kilogram, including $$\frac{1}{2}$$,  $$\frac{1}{4}$$,  $$\frac{3}{4}$$, and relate these to the number of grams
• solve problems, including those involving commonly used fractions of a kilogram (Problem Solving)
• record masses using kilograms and grams, eg 1 kg 200 g

### Background Information

Refer to background information in Mass 1.

### Language

Students should be able to communicate using the following language: mass, measure, scales, kilogram, gram.

The term 'scales', as in a set of scales, may be confusing for some students who associate it with other uses of the word 'scales', eg fish scales, scales on a map, or musical scales. These other meanings should be discussed with students.