Maths. Ask pupils to visualise big numbers. The world's population is 6.3 billion.
If you counted up to 6.3 billion, counting one number each second, how many years would it take? If each person's written name averaged 50mm in length, how long would the list be in kilometres if they were all written next to one another? How big is this compared with the circumference of the earth, or the length of a pupil's journey to school?
The article can stimulate a discussion of the dangers of extrapolation in the face of unpredictable factors, such as the arrival of Aids. How could the Ehrlichs's predictions be so wrong? What is the percentage error between their estimate of 10 billion and today's prediction? Discuss the reliability of current estimates. Are they more likely to be over-estimates or under-estimates? In countries where women bear an average of six children, at what rate will population grow? What other factors need to be considered? This could be investigated using a spreadsheet. At sixth-form level this leads to work involving modelling with differential equations.
A secondary school class project could be to use graphs to illustrate the data given in the article.
Population is a theme of the key stage 3 PoS (6f) and an integral component of GCSE and A-level. There are also plenty of opportunities to teach about migration and population as part of place studies at KS2 (3a-g).
An interesting starter activity is to give pupils key statistics (birth and death rates, Aids infection) for a set of countries but without telling them which is which.
The causes of migration can be classified as "push" (repulsion) or "pull" (attraction). Take your class into the school hall. Split them into two groups. Let each in turn stand in the middle while you call out factors such as "famine", "higher wages" and they run to either the "push" end or "pull" end of the hall.
Some fascinating websites allow you to examine population. For example: www.census.govipcwwwidbpyr.html This is a good topic for considering "futures geography", what will a country be like in 50 years time?
This article has excellent links with citizenship. These range from moral questions about the use of resources to ways in which individuals can resolve a problem, for example through buying fair trade products.
Design and technology
Key stages 1-2: ask students to design a poster or leaflet prompting households to consider whether they should leave the tap on while brushing their teeth and how much they would save if they turned it off.
KS3: a design project on reducing water use at home can make students consider its moral and social issues.
KS4: ask students to think of the waste created by their school and find ways of reducing it. Students could create paper recycling bins which a committee collects each week and the council picks up. If they won't collect get pupils to write to their MP.
In Germany manufacturers have to make their products sustainable.
Sixth-formers could petition our government to change the law.
KS3-4 and A-level: Using the data on population growth and the environmental impact of population, students could update information in popular textbooks, as in Biology by Michael Roberts.
KS3-4: Calculate the cost of electricity used by domestic appliances and develop ideas about the importance of wind, wave and solar power.
KS4 and A-level: Use Abraham Lincoln's remark (above) as basis for a research task, linking energy transfer, respiration or the carbon cycle.
The quotation could also make an essay title.
Discuss the impact of Aids and the differences between the US and other countries.
Pupils could hypothesise about the impact on a country of a reduction in life expectancy to 33 (as in Zimbabwe) or 41.5 (in South Africa).
Another research exercise and essay task for sixth-formers would be the world-wide distribution of centenarians.
All key stages: a school assembly on population growth and global citizenship.