1. CollectProcessDiscussPlan World Population Title slide

2. CollectProcessDiscussPlan World Population Every second the number of people in the world grows. How many people do you think there are in the world right now? How many babies do you think will be born during this lesson? Online population clock Population clock

3. CollectProcessDiscussPlan World Population If the population is increasing, will we ever run out of space? If so, when might it happen? What is the maximum number of people the world can support? To help answer this scientists have studied the way bacteria grow on a petri-dish filled with nutrients. They start with a few bacteria and give them lots of food (nutrients) and space in which to multiply. Petri dish model

4. CollectProcessDiscussPlan Lets use a computer model to see what happens as the bacteria multiply over time. World Population When each bacterium has had enough nutrients it divides in two. If it does not manage to take in enough nutrients it dies. Time Number minutes 0 1 20 3 40 6 60 10 80 19 100 38 120 66 140 89 160 104 180 131 200 157 220 180 240 183 260 181 Task : Can you plot the population number against time? Time Number Nutrients Bacterium Dead space Bacterial growth

5. CollectProcessDiscussPlan World Population Your graph should look something like this. Chart showing population of bacteria against time 300 What do you think will happen to the bacteria next? 350 ? Data plotted

6. CollectProcessDiscussPlan World Population What is happening during the ‘stationary’ phase? Hint: as quickly as new bacteria are appearing… Scientists have discovered from growing different cultures of bacteria that they follow the same pattern: The chart is often broken up into four phases. Time Number Lag Log Stationary Death Four phases

7. CollectProcessDiscussPlan World Population Time Number Do you think that the human population grows in the same way as the bacteria? Time Number Perhaps the World’s Population will move into the death phase? 2006? Is it still racing up or has it levelled off? Human growth curve

8. CollectProcessDiscussPlan World Population We can think of each country (or continent) as a separate petri dish (of different sizes). Collecting data for the whole world is difficult. Are there parts of the world that have increasing populations, others which are steady and others in decline? Countries as dishes

9. Something you believe might be true is called a hypothesis. For example “I believe Mexico has a steady population.” CollectProcessDiscuss Which parts of world do you think might have an increasing population? a steady population? a declining population? Something you believe might be true is called a hypothesis. To help investigate a hypothesis, we can use the Problem Solving Approach… Plan World Population Making hypotheses Time Number steady increasing declining

10. First we decide what problem to solve and what First we decide what problem to solve and what data we need CollectProcessDiscuss Process Plan Collect Then we collect suitable data. Then we examine our data and make it easier to understand. We report back what we found – and compare it to what we expected. Plan World Population PSA cycle

11. CollectProcessDiscuss Plan World Population Important: It doesn’t matter if your hypothesis is wrong, because you’ll always learn something new from the data! Which part of world are you going to consider? What do you think is happening to the population there? What might be causing the population to grow like that? Write your ideas down, see if you can form them into a hypothesis. “I think that….because….” Your hypothesis

12. Collect ProcessDiscuss PlanCollect How far back in time should/can we go? What information do we need to collect? World Population Types of data What data to collect?

13. Can we use primary data or secondary data? Collect ProcessDiscuss PlanCollect World Population Data we collect for ourselves Data that someone else has collected PRIMARY DATASECONDARY DATAvs. What sort of data can we use in this investigation? There are good and bad things about both types of data. Can you think what some of them are? Types of data

14. Discuss Process PlanCollectProcessDiscuss Plan Collect The Problem Solving Approach You are now here. PSA cycle

15. Collect ProcessDiscussPlan World Population A number of websites contain information on population sizes. prb.org census.gov wikipedia.org unfpa.org It is difficult to find the world’s actual population; we use estimates based on national censuses and calculations using birth and death rates. Suitable sources

16. Collect ProcessDiscussPlan World Population www.rsscse.org.uk/qca/population First choose “Total Population” Then select a country Choose the years you want to use. (1950 onwards) A webpage will appear with your selected data. US census

17. Collect ProcessDiscussPlan World Population www.rsscse.org.uk/qca/population A webpage will appear with your selected data. If you want to use this data as a spreadsheet (to use in Excel) then click on File  Save As. Then rename the file to population.CSV Creating a CSV

18. Discuss Process PlanCollectProcessDiscuss Plan Collect The Problem Solving Approach You are now here. PSA cycle

19. Process PlanCollectDiscuss World Population Now that we have collected some data, what can we do to make it easier to understand? We will plot time on the x-axis We will plot population on the y-axis We can draw a line graph of the data Plotting data

20. Process PlanCollectDiscuss World Population Mexico 0.00 20.00 40.00 60.00 80.00 100.00 120.00 19501960197019801990200020102020 Year Millions of people +10 +14 +16 +15 +13 predicted How would you describe the growth of this country since 1950? Lets see how the population has grown every 10 years. By how much will it grow between 2000 and 2010? Looking at growth

21. Discuss Process PlanCollectProcessDiscuss Plan Collect The Problem Solving Approach You are now here. PSA cycle

22. Discuss PlanCollectProcess Discussion World Population Describe the growth curve for your chosen population. Where do you think the country is on the growth curve? What do you think will happen to this country over the next 10 years (decade)? 100 years (century)? Could you work out the maximum population your country is likely to reach? Discussing findings Time Number

23. Discuss Process PlanCollectProcessDiscuss Plan Collect The Problem Solving Approach You are now here. You can build on your investigation by continuing here... PSA cycle

24. How fast is the population growing in your country compared to neighbouring countries? richer or poorer countries? PlanCollectProcess Discussion World Population Discuss You may like to continue your investigation by considering household size in the UK or population pyramids in different countries: Some additional investigations: Population pyramids Household numbers Number of women Size of family Extending the work

25. PlanCollectProcess Discussion World Population Discuss Household sizes What does it show? Describe the pattern that you can see. What impact could decreasing household size have? What other factors relating to household size could you investigate? As populations grow, space and available housing becomes important. Consider at the graph below:

26. PlanCollectProcess Discussion World Population Discuss Household sizes The graph below shows the change in household size since 1971. Can you create a similar graph for your class? What is the mean household size in your class? How do you compare to the national picture? 6+ 5 4 3 2 1 Key

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28. Discussion World Population : Pyramids 12 0- 4 10-14 20-24 30-34 40-44 50-54 60-64 70-74 80-84 90-94 100+ Age range Percentage 84 0- 4 10-14 20-24 30-34 40-44 50-54 60-64 70-74 80-84 90-94 100+ Age range 12 048 Census data from each country can be used to count how many women are 0-4, 5-9, 10-14 etc. A bar chart can be drawn for men in the same country. PlanCollectProcessDiscuss Population Pyramids

29. What shape would you expect the pyramid to become as the population continues to fall? Discussion World Population 40 45 50 55 60 65 19501960197019801990200020102020203020402050 Year Millions of people 12 0- 4 10-14 20-24 30-34 40-44 50-54 60-64 70-74 80-84 90-94 100+ Age range Percentage 84048 We can plot the population curve below using current and estimated numbers. Above will show the pyramid displaying the breakdown of population by age and gender. How is the pyramid related to the growth of the population? Fairly quick growth Slowing Falling PlanCollectProcessDiscuss Curves & Pyramids

30. Discussion World Population What do you think the pyramids are like for countries which you have investigated? Different parts of the world have different population pyramids. A country’s pyramid can be used to suggest if the country is growing, steady or in decline. PlanCollectProcessDiscuss Countries & Pyramids

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