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ERIC Number: EJ961652
Record Type: Journal
Publication Date: 2011
Pages: 5
Abstractor: ERIC
Reference Count: 7
ISSN: ISSN-1326-0286
"Twenty Percent Free!" So How Much Does the Original Bar Weigh?
Hawera, Ngarewa; Taylor, Merilyn
Australian Primary Mathematics Classroom, v16 n4 p3-7 2011
Developing critical numeracy is important in a society where mathematics plays a particular and significant role. One way of helping learners to develop the level of numeracy required to participate in society is by exploring ideas embedded in rich, accessible tasks. These can be linked to contexts that have relevance in their lives. One mathematics idea widely employed in everyday living is percentages. A common context for exposure to percentages is where people act as consumers. Percentages are often presented to entice and sway people to make decisions about the purchase of a particular product or service. Understanding percentages and what they represent is therefore critical for appreciating the consequences of any decisions that are made. One way of exploring percentages is by examining readily available supermarket products that proclaim greater value or a larger quantity for the same dollar amount. This is a common manufacturing and marketing strategy for encouraging people to purchase a particular product. In this article, the authors explore a task that links to the context of buying a chocolate bar which indicates that the purchaser would be getting 20% more than the original bar, for the same price as the original one. A chocolate bar may seem a somewhat frivolous context, but it is a worthwhile opportunity for supporting students to develop their thinking about percentages greater than 100 percent. (Contains 3 figures.)
Australian Association of Mathematics Teachers (AAMT). GPO Box 1729, Adelaide 5001, South Australia. Tel: +61-8-8363-0288; Fax: +61-8-8362-9288; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Identifiers - Location: Australia