Earth and Environmental Science 11–12 · Year 11
Where the Earth’s water is: a 1000 mL model of oceans, ice, groundwater and rivers
Module 4: Human Impacts
The idea
Only a fraction of a per cent of all water is fresh, liquid and at the surface, which is the quantity that people, plants and animals draw on.
What you need
- 1 L measuring cylinder of water (all the Earth’s water), a 50 mL cylinder, two 10 mL cylinders, a 1 mL syringe or dropper
- salt to make the ocean share visibly salty, blue colouring
- labels: oceans, saline groundwater and saline lakes, ice caps and glaciers, groundwater, surface and other fresh water
How to do it
- From the volumes in the USGS table (oceans 1 338 000 000 km³; saline groundwater 12 870 000 km³ and saline lakes 85 400 km³; fresh water 35 029 110 km³ in all; total 1 385 984 510 km³), calculate each share of 1000 mL, then split the fresh share by the USGS percentages of fresh water (68.7 % ice, 30.1 % groundwater, 1.2 % surface and other).
- Measure the saline groundwater and saline lakes share into a 10 mL cylinder and the fresh-water share into the 50 mL cylinder, leaving the oceans in the litre cylinder; then split the fresh water into ice, groundwater and surface water in the smaller vessels.
- Photograph the line-up with labels and volumes.
- Estimate the share of the surface water that is in rivers (0.49 % of surface fresh water) and comment on why it is invisible at this scale.
What you should see
Oceans 965.4 mL, saline groundwater and saline lakes 9.3 mL and fresh water 25.3 mL, which together make the whole 1000 mL (USGS rounds the fresh share to 2.5 %); of the fresh water, ice 17.4 mL, groundwater 7.6 mL and surface and other fresh water 0.3 mL, a few drops; the river share is about 0.0015 mL, below what a dropper can show. The learner states that surface and other fresh water is 0.03 % of all water, that the USGS table places about two thirds of it in ground ice and permafrost, and that fresh groundwater, 0.76 % of all water, far exceeds all the fresh water at the surface.
What changes
This activity lists no variables to change, measure and keep the same.
Common misconceptions
Each of these ideas is wrong, and the activity is a chance to test it.
- Most fresh water is in rivers and lakes.
- Groundwater is a small resource compared with rivers.
Safety card
Hazards
No hazard is listed.
Controls
No control is listed.
Note
No hazardous chemicals or heat sources: record the activity in the school's RiskAssess risk assessment, following the NSW Department of Education Science safety and compliance page; the Chemical Safety in Schools package is not triggered.
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
- Earth and Environmental Science Stage 6 Syllabus (2017), NESA; current, replaced by the 11–12 Syllabus (2025) from 2028EES11-11EES11/12-1EES11/12-2EES11/12-3
- Earth and Environmental Science 11–12 Syllabus (2025), NESA; to be implemented from 2028, not yet taughtEES-11-03
- Australian Curriculum v9No Australian Curriculum v9 code is listed.
Sources
The pages the author read to write this activity.