# YEAR 3 MATHS FOCUS

## MEASUREMENT AND GEOMETRY

Mass

Learning Experiences

Mass

## MASS

OUTCOME

A student:

MA2-12MG: measures, records, compares and estimates the masses of objects using kilograms and grams

TEACHING POINTS | 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, e.g. 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 (although Gabi disagrees as this caused troubles for her at university). Weight is a force that changes with gravity, while mass remains constant. |

## EXPECTATIONS OF ATTAINMENT

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, Critical and creative thinking} |

Learning Experiences

to be added