Activity Introduction

water-heroQuick summary: As a ‘thought starter’, students watch a short clip about a method of open-sea farming created by Sealeaf. To investigate the real-world application of this innovative farming method, students explore global mean sea levels from 1880 to 2013. Using a graph containing authentic data, your class will consider historic trends, calculate gradients of line segments, and comment on what the gradient represents. Finally, students will hypothesise who will be most affected by future sea level rise.

Learning goals:

  • Students understand how gradient and rate of change relates to authentic data.
  • Students know how to calculate midpoints and gradient.
  • Students discover the impact of sea level rise on a global scale and how the levels are changing over time.
  • Students take personal action by undertaking further investigation and increasing community awareness.

21st century skills:

BLUE_coral reef_sci_yr9

Australian Curriculum Mapping

Content descriptions:

Year 9 Mathematics:

  • Solve problems involving direct proportion. Explore the relationship between graphs and equations corresponding to simple rate problems (ACMNA208)
  • Find the midpoint and gradient of a line segment (interval) on the Cartesian plane using a range of strategies, including graphing software (ACMNA294)

Syllabus outcomes: MA3‑2WM

General capabilities: Numeracy, ICT Capability, Critical and Creative Thinking

Cross-curriculum prioritySustainability OI.1

Relevant parts of year 9 achievement standards: Students make sense of the position of the mean and median in skewed, symmetric and bi-modal displays to describe and interpret data. Students find the distance between two points on the Cartesian plane and the gradient and midpoint of a line segment.

Topic: Number and Algebra, Climate change

Time required: 60 min.

Level of teacher scaffolding: Low – teacher may need to demonstrate skills.

Resources Required: Student worksheet, internet access, and Climate Change Digital Toolbox.

Keywords: Cartesian plane, mid-point, gradient, coordinate points, data, sea level, climate change.

Cool Australia’s curriculum team continually reviews and refines our resources to be in line with changes to the Australian Curriculum.


Teacher Worksheet

sea-grass-biodiversity-heroTeacher Preparation

Learning intentions: 

  • Students will understand how to read data from a graph
  • Students will calculate mid-point and gradient and comment on these in context
  • Student will discover the impact of sea level rising on a global scale

Success criteria: Students can...

  • ...describe the key features of the graph.
  • ...calculate mid-point and comment in context.
  • ...calculate gradient and explain its context.
  • ...conduct research for reliable sources of information. 

Teacher content information: This lesson is based on data sourced from the CSIRO and the Antarctic Climate & Ecosystem Cooperative Research Centre's (ACECRC) sea level specific website 'Sea Level'. The following background information can be found on the homepage of the website. For more information on projections, data, and impacts please visit the site.

Humans have always loved the coast. Coastal regions, particularly some low-lying river deltas, have very high population densities. In exces

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Student Worksheet

Thought starter: Albert Einstein said, "We cannot solve our problems with the same thinking we used when we created them".

Part A: Sea-levels on the Rise

1. Watch the Sealeaf project video below.

2. Share with a partner 'what you like' and 'what puzzles you' about the Sealeaf project.

Sealeaf - Short Cut (

Many observations show that the ocean has been changing over the last several decades. One aspect of this change is ocean warming, which results in an increase of ocean volume through thermal expansion. There has also been addition of water from glacier and ice sheets, as well as changes in storage of water on or in the land (e.g. retention of water in man-made dams and extraction of water from aquifers). Together, these factors result in the sea level changing. This graphs shows in global mean sea level from 1880-2012. 

For more information you may like to read the CSIRO's Sea Level page.

Part B: Calculating Sea-levels 

Use this graph to help a

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