Since 1900, Australia has recorded 170 bull shark bites, and not one happened in a month when the sea was cooler than 19°C (66°F). As the ocean warms, water that warm reaches further south and lasts longer each year.
| 1900s | 6.4 | |
|---|---|---|
| 1910s | 6.5 | |
| 1920s | 6.2 | |
| 1930s | 6.8 | |
| 1940s | 6.9 | |
| 1950s | 7.0 | |
| 1960s | 6.6 | |
| 1970s | 7.1 | |
| 1980s | 7.8 | |
| 1990s | 8.1 | |
| 2000s | 8.6 | |
| 2010s | 9.1 | |
| 2020s | 9.3 |
Dashed line = 6 months, half the year
Ages 12 to 15 (Australia Years 7–9, US Grades 6–9, UK Years 8–10) · 50–60 minutes · individual or pairs
A change in one non-living factor, water temperature, changes where and when a species lives. Patterns in data can support or challenge an explanation. Apparent contradictions can both be true.
| Australia (v9) | AC9S7U02 (models of ecosystems; how changes in abiotic and biotic factors affect populations); AC9S7I05, AC9S7I06, AC9S7I07 (analysing data, evaluating claims and constructing evidence-based arguments; the Year 8 and 9 equivalents are AC9S8I05–07 and AC9S9I05–07). Mathematics: percentages and reading data displays. |
|---|---|
| United States (NGSS) | MS-LS2-1 (effects of resource availability on organisms and populations); MS-LS2-4 (changes to physical or biological components of an ecosystem affect populations). |
| England (National Curriculum) | Key Stage 3 science: Interactions and interdependencies; Working scientifically (analysis and evaluation). Key Stage 3 maths: percentages and interpreting data. |
| International Baccalaureate | MYP Sciences criteria B (inquiring and designing) and C (processing and evaluating); MYP Individuals and societies: environmental change. |
| Other curricula | New Zealand: Science, Living World and Nature of Science (investigating in science). Canada (Ontario): Grade 7 Interactions in the environment. Cambridge Lower Secondary Science: ecosystems and thinking and working scientifically. |
| Global goals | UN Sustainable Development Goals 13 (Climate action) and 14 (Life below water); UNESCO Education for Sustainable Development. |
Mapped by topic. Check your own syllabus for local codes.
| Phase | Time | What happens |
|---|---|---|
| Engage | 5 min | Show the hero headline: 170 bites, not one below 19°C. Ask what could explain it. |
| Explore | 15 min | Read the chart and map; questions 1–2. |
| Explain | 10 min | Discuss range and season, and why fewer sharks worldwide doesn't mean fewer near one coast. |
| Elaborate | 15 min | Questions 3–4: competing explanations and how to test one. |
| Evaluate | 10 min | Question 5, then exit ticket: one thing the data shows and one thing it can't. |
Printed sheet; calculators. Optional: the 19 Degrees page for the interactive beach chart.
Support: Work through question 1 as a class; give sentence starters for questions 3–4 ("Both can be true because...", "To test this I would compare...").
Extension: Use the downloadable CSV to make your own chart for another beach and describe the trend.
Use the answer guide. Question 1 checks calculation, questions 3–4 reasoning with evidence, question 5 communication.
This topic involves injuries and deaths. Some students may know someone affected by a shark bite or a drowning. Keep the focus on patterns and staying safe, avoid graphic images and news footage, let students step out if they need to, and follow your school's wellbeing procedures. Sharks hold cultural significance for many Indigenous peoples, including Aboriginal and Torres Strait Islander, Māori, Native Hawaiian and other Pacific peoples; if you explore this, use resources developed with or approved by local communities.
Data: Australian Shark-Incident Database (Taronga Conservation Society Australia and Flinders University); HadISST sea temperature (UK Met Office); Pacoureau et al. 2021; Surf Life Saving Australia. From 19 Degrees, free and open source. © 2026 Blake Erickson.