How people change the environment: forests, rivers, cities and pollution
Grade 9 Social Studies Worksheet - Building Confidence
Circle the best answer.
Read this first
Card A, forest facts (FAO, Global Forest Resources Assessment 2020)
The world has 4.06 billion hectares of forest, 31% of its land. Net forest loss was 7.8 million hectares a year in 1990–2000, 5.2 in 2000–2010 and 4.7 in 2010–2020. Deforestation, clearing forest for other land uses, was 12 million hectares a year in 2010–2015 and 10 million in 2015–2020. About 420 million hectares of forest were turned to other land uses from 1990 to 2020. Net loss is forest lost minus forest gained by planting and natural regrowth. Card B, chain: people clear forest for farmland, mines, reservoirs and cities; that gives more land for crops and other uses, and less forest, which puts wildlife habitats and the livelihoods of forest communities at risk.
Noah reads the word 'deforestation' on Card A. What does it mean?
- Clearing forest so the land can be used for something else, such as farms, mines or cities
- Forest lost minus forest gained by planting and natural regrowth, counted across a year or a decade
- Any loss of forest area, including forest that is lost and then regrows in the same place later
- Planting trees on land that was cleared, so that the forest area grows back again over the years
Net forest loss was 7.8, then 5.2, then 4.7 million hectares a year (1990–2000, 2000–2010, 2010–2020). What does Card A support, Ren asks?
- Forest began growing back by 2020, since the net loss figures fell below 5 million hectares a year
- Forest kept shrinking in each decade, but more slowly each time, so the loss slowed without ending
- Forest loss ended in 2010, since each decade after the first showed a smaller loss than before
- Deforestation fell from 7.8 to 4.7 million hectares a year, since the clearing slowed by that amount
Deforestation was 10 million hectares a year in 2015–2020, but net loss was 4.7 million a year in 2010–2020. Why is net loss smaller, Tala asks?
- The two periods differ, so net loss and deforestation cannot be compared with one another
- Net loss counts just the forest cleared for cities, while deforestation counts clearing for farms, mines and reservoirs too
- Net loss is measured on a smaller forest area than deforestation is, so its figure comes out smaller
- Net loss subtracts the forest gained by planting and natural regrowth from the forest cleared, so it is smaller
Card B follows a chain from clearing. Which pair of effects comes from the same act of clearing, Zee asks?
- More land for crops, and more forest, since the cleared land is soon replaced by planted trees
- More land for crops and other uses, and less forest, which puts habitats and livelihoods at risk
- Less land for crops and more reservoirs, which put the livelihoods of forest communities at risk
- More forest for habitats, and less land for crops, which puts the livelihoods of farmers at risk
About 420 million hectares of forest were turned to other uses over 30 years (1990–2020). Does that fit Card A's 12 and 10 million a year, Ari asks?
- Yes: 12 and 10 million add to 22 million, and the rest of the 420 million came from regrowth
- No: 12 and 10 million a year over 30 years would give 360 and 300 million, so far from the 420 million total on the card
- Yes: 420 million over 30 years averages 14 million a year, above 12 and 10, so earlier years had more clearing
- No: 420 million is a yearly figure, so it is far larger than 12 and 10 million hectares a year
A village clears forest for farmland. Which statement matches Card B, Bo asks?
- It gains land for crops with no cost, since the forest is replaced by fields that feed people near the village
- It has no clear gain or cost, since Card B names the uses and not the effects of clearing
- It gains land for crops, while wildlife habitats and the livelihoods of forest communities are put at risk
- It loses land for crops but gains habitats, since cleared forest returns to wildlife in a few years
Esme's note: 'The world lost 4.7 million hectares a year to deforestation in 2010–2020.' Which fix fits Card A?
- Change 4.7 to 31, since 31% of land is forest and so that figure describes the loss for the decade
- Keep it, since net loss and deforestation both describe the forest that was cleared in those years, just under different names
- Change 'lost' to 'gained', since a figure that is below 5 million a year is a gain and not a loss
- Change 'deforestation' to 'net loss': deforestation was 12 then 10 million a year, with regrowth offsetting part
Which statement about the world's forest is supported by Card A, Jun asks?
- Forest covers 4.06 percent of the world's land, since the figure given is 4.06 and is read as a percent, as the card states it
- Forest covers 31% of the world's land, which is nearly a third, so most land is something other than forest
- Forest covers most of the world's land, since 4.06 billion hectares is a very large area for forest
- About 420 million hectares, a third of the forest, were turned to other uses between 1990 and 2020
Deforestation was 12 million hectares a year in 2010–2015. About how much was cleared in those five years, Kira asks?
- About 600 million hectares, since 12 million a year for five years is moved over by one place
- About 60 million hectares, since a rate of 12 million a year for five years makes 60 million
- About 2 million hectares, since the rate fell from 12 to 10 million and the difference is 2 million
- About 12 million hectares, since the figure on Card A is the amount for the whole period
Which claim is best supported by Card A, Milo asks?
- Clearing doubled between the periods, since 12 million a year in the first is read as 6 million in the second
- Clearing slowed from 12 to 10 million hectares a year between 2010–2015 and 2015–2020, but it continued
- Clearing stopped by 2020, since the yearly figure fell between the two five-year periods on the card
- Clearing is the same in both periods, since 12 and 10 million a year are close enough to be treated as equal