How people are changing Earth's systems
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
Read this first
Where rain goes as land is paved (USGS, from FISRWG 1998)
Ground cover Evapotranspiration Runoff Shallow infiltration Deep infiltration Natural ground cover 40% 10% 25% 25% 10–20% impervious 38% 20% 21% 21% 35–50% impervious 35% 30% 20% 15% 75–100% impervious 30% 55% 10% 5% A student tells Esme that paving only changes surface water. Which reply is supported by the table?
- No; paving cuts runoff from 55% to 10% and raises deep infiltration from 5% to 25% of rain
- Yes; the sole column that changes in the table is the runoff column, rising from 10% to 55%
- No; paving also cuts evapotranspiration from 40% to 30% and deep infiltration from 25% to 5%
- Yes; paving moves water between the same columns, so the totals in each row change a little
The ocean absorbs about 30% of released CO₂, surface pH has fallen 0.1, and shell builders find fewer carbonate ions. A student tells Jun that the ocean's 30% uptake means people's CO₂ no longer affects other systems. Which reply is supported by the card?
- Supported; 30% uptake leaves the air unchanged, even though the seawater turns more acidic
- Not supported; the ocean absorbs the CO₂ and its pH rises by 0.1, which helps shell builders
- Not supported; uptake lowers pH by 0.1 and carbonate ions, so another system changes
- Supported; the CO₂ vanishes once the ocean absorbs it, so no other system changes
Deforestation was 16 million hectares a year in 1990–2000 and 10 million hectares a year in 2015–2020. A student tells Kira that forests are no longer shrinking, since deforestation fell. Which reply is supported by the card?
- No; the rate rose from 10 million to 16 million hectares a year between the two periods shown on the card
- No; the rate fell by 6 million hectares a year, but 10 million hectares a year are still cleared
- Yes; a lower rate means the loss has stopped, so forests are no longer shrinking anywhere in the world
- Yes; 16 − 10 = 6 million, so 6 million hectares a year are now regrown after being cleared, which offsets the loss
Where rain goes as land is paved (USGS, from FISRWG 1998)
Ground cover Evapotranspiration Runoff Shallow infiltration Deep infiltration Natural ground cover 40% 10% 25% 25% 10–20% impervious 38% 20% 21% 21% 35–50% impervious 35% 30% 20% 15% 75–100% impervious 30% 55% 10% 5% Model data: 3 inches of rain fall on 40 acres at 35–50% impervious cover. How deep must a 2-acre pond be to hold the runoff, by Luz's math? (1 acre-foot is 12 acre-inches.)
- About 1.5 feet
- About 0.15 foot
- About 5 feet
- About 18 feet
Card (example data)
10 billion tons of carbon are released in a year. NOAA: the ocean absorbs about 30%. Model data: land plants take up 25%.
Model data: 10 billion tons of carbon are released in a year. The ocean takes 30% and land plants take 25%. How much stays in the air, by Milo's math?
- About 5.5 billion tons
- About 7 billion tons
- About 2.5 billion tons
- About 4.5 billion tons
Where rain goes as land is paved (USGS, from FISRWG 1998)
Ground cover Evapotranspiration Runoff Shallow infiltration Deep infiltration Natural ground cover 40% 10% 25% 25% 10–20% impervious 38% 20% 21% 21% 35–50% impervious 35% 30% 20% 15% 75–100% impervious 30% 55% 10% 5% Model data: a 2-acre lot gets a 2-inch storm. Going from woodland to 75–100% impervious cover, how many more gallons run off, by Noah's math? (1 acre-inch is about 27,000 gallons.)
- About 108,000 gallons
- About 4,900 gallons
- About 59,400 gallons
- About 49,000 gallons
Rain garden test (example data)
Neighborhood Lots with rain gardens Runoff cut A 20% 14% B 20% 5% C 20% 16% A model predicts that rain gardens on 20% of lots cut runoff by 15%. What do the measurements say about the model, by Pia's reading?
- The model is proven right, since the three measured cuts average close to its 15% prediction
- The model is wrong, since one of the three neighborhoods differs from it by 10 points
- Two neighborhoods match within 1 point; B differs by 10, so check why B differs
- The measurements are wrong wherever they differ from the model, so the model should be kept
Claim: ocean surface pH has fallen about 0.1 because the ocean takes up CO₂ released by people (NOAA). Which evidence would best show that falling ocean pH is linked to CO₂ uptake and not to a natural swing, by Ren's reading?
- One month of pH readings from a single buoy near the coast, taken in summer and spring
- The total volume of the ocean, compared with the volume of the air above its surface
- Decades of pH readings that fall as air CO₂ rises, matching the chemistry of dissolved CO₂
- A museum photo of shells from a different ocean and a different era in Earth's past
Two test plots after the same rain (example data)
Plot Cover Slope Runoff share Plot A Paved 8% 55% Plot B Grass 2% 10% A student says the results show paving causes the extra runoff. What flaw weakens that claim, by Tala's reading?
- Plot B had less runoff, which shows that grass makes the rain water vanish from the plot
- The plots differ in slope as well as cover, so the steeper slope may explain the runoff
- Runoff is measured as a share of rain, which cannot be compared between two separate plots
- The plots got the same rain, so the test cannot show any difference between the two covers
Card
Paving raises runoff (USGS). Clearing removes plants that store carbon (NASA). Dams trap sediment (USGS). Fuel CO₂ moves into the ocean (NOAA).
Which summary links each change to the systems it affects, by Bo's reading?
- Paving: air and life. Clearing: water and land. Dams: water and land. Fuel CO₂: air and ocean
- Paving: land and water. Clearing: life alone. Dams: water alone. Fuel CO₂: air alone
- Paving: land and water. Clearing: life and air. Dams: air and life. Fuel CO₂: air and ocean
- Paving: land and water. Clearing: life and air. Dams: water and land. Fuel CO₂: air and ocean