describes mathematical situations using everyday language, actions, materials and informal recordings
uses concrete materials and/or pictorial representations to support conclusions
describes and compares the masses of objects using everyday language
- Use direct and indirect comparisons to decide which is heavier, and explain their reasoning using everyday language (ACMMG006)
- identify the attribute of 'mass' as the amount of matter in an object
- use everyday language to describe objects in terms of their mass, eg heavy, light, hard to push, hard to pull
- use comparative language to describe mass, eg heavier, lighter, heaviest, lightest
- identify an object that is heavier or lighter than another (Communicating)
- compare and describe two masses, such as by pushing or pulling
- compare two masses directly by hefting, eg 'This toy feels heavier than that one'
- predict which object would be heavier than, lighter than, or have about the same mass as another object and explain reasons for this prediction (Communicating, Reasoning)
- investigate the use of hefting in practical situations, eg the practice used by Aboriginal people of hefting duck eggs to determine whether ducklings will be male or female (Problem Solving)
- record comparisons of mass informally using drawings, numerals and words
In Early Stage 1, students develop an awareness of the attribute of mass and some of the language used to describe mass. Opportunities to explore mass concepts and understand the action of a two-pan balance occur in play situations, such as a seesaw in a children's playground.
Students in Early Stage 1 should only be comparing two objects that are quite different in mass. Early experiences often lead students to the conclusion that large things are heavier than small things and that if two things are the same size and shape, then they will have the same mass. To develop beyond this, students need to have experiences with objects that are light and large, heavy and large, light and small, heavy and small, and large but lighter than a smaller object.
When students are asked to compare the masses of two objects of equal mass and can consistently say that the objects are equal in mass though their shapes are different, they are conserving mass.
Aboriginal communities were traditionally able to determine whether ducklings would be male or female by hefting duck eggs (female eggs are heavier), as well as by considering other factors such as size, shape and temperature.
Students should be able to communicate using the following language: mass, matter, heavy, heavier, heaviest, light, lighter, lightest, about the same as, hard to push, hard to pull.
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.
'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.