## Mathematics Support Materials

### Mathematics snapshot: Save our canteen

Mathematics/Statistics and Probability/Data representation and interpretation

Content Description Relevant aspects of the Achievement Standards

Construct and compare a range of data displays including stem-and-leaf plots and dot plots (ACMSP170)

Students identify issues involving the collection of continuous data. They describe the relationship between the median and mean in data displays.

Students calculate mean, mode, median and range for data sets. They construct stem-and-leaf plots and dot-plots.

### Nature of the assessment

Teacher observation of class activity

### Purposes of the assessment

To assess students’ ability to summarise and display data in an appropriate manner; and to use graphs to inform decision making.

### Stage in the teaching sequence

Mid-way in a lesson sequence

### Background

There had been some discussion in the school that the school canteen would only open for three days a week. As the students felt strongly about the issue the teacher decided to use it as a context to assess his students’ ability to work with data. However, he decided to mock-up data rather than to try to use actual data.

Context: The school canteen needs to save money and only open for three days a week.

Stimulus: A table detailing the canteen takings per day of the week, for an eight week period.

Task: The students were required to summarise the data in a table; use the data to construct a pie chart, a line graph and bar graph; explain which graph was the most appropriate for the purpose and make a recommendation for which three days the canteen should open.

### Assessment criteria

• correctly summarises data
• uses appropriate scale
• accurately graphs data
• correctly labels graphs
• explains which is the most appropriate graph in the given context.

### Using the information

The teacher marked the students’ work and gave detailed feedback. He also used the task to evaluate his teaching of the topic and made notes of teaching points as he marked.