Feedback loops: changes that grow or shrink themselves

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   “Loop diagram:” Melting sea ice uncovers dark ocean, which absorbs more sunlight and melts more ice. What does this loop do, by Ari's reading?

   • It is not a feedback; it happens once
   • It shrinks the melting: a negative feedback
   • It is negative, since more melting is bad
   • It grows the melting: a positive feedback
2. 2.

   When Kira gets hot on a run, Kira sweats, and the sweat evaporating cools the skin. What kind of loop is this?

   • Negative: it shrinks the change in body temperature
   • Positive: getting hot makes you hotter
   • Negative: it makes the body colder than before the run
   • Positive, since sweating is good for you
3. 3.

   Sea ice reflects 50 to 70% of sunlight; open ocean reflects about 6% (NSIDC). Which surface absorbs more sunlight, by Jun's reading?

   • Open ocean
   • They absorb the same amount
   • Sea ice, since it reflects more
   • Sea ice, since it is colder
4. 4.

   A surface has an albedo of 0.6. What does that mean, by Milo's reading?

   • It reflects 60% and absorbs 40%
   • It reflects 6% of sunlight
   • It is 60% ice
   • It absorbs 60% and reflects 40%
5. 5.

   A + link means both change the same way; a − link means opposite ways. Which sign fits "warmer air → more water vapor," by Noah's reading?

   • −, since water vapor is a bad thing
   • No sign; vapor does not depend on temperature
   • +, since both go up together
   • −, since one goes up and one goes down
6. 6.

   Link: more sea ice → sunlight absorbed, with a blank sign. Which sign fits the link "more sea ice → sunlight absorbed," by Pia's reading?

   • +, since both of them change
   • +, since ice is good for the planet
   • −: more ice, less sunlight absorbed
   • +, since ice absorbs more sunlight
7. 7.

   Which sign fits the link "more plant growth → carbon dioxide in the air," by Ren's reading?

   • −: more growth, less carbon dioxide
   • +, since plants are helpful
   • +, since both are about carbon
   • No sign; plants do not affect the air

8. Read this first

   September Arctic sea ice (model data based on NSIDC)

   Year	Extent (million km²)
   1980	7.8
   2000	6.3
   2020	3.9

9. 8.

   The table shows September Arctic sea-ice extent. What happened from 1980 to 2020, by Tala's reading?

   • It grew from 1980 to 2020
   • It shrank to zero by 2020
   • It shrank to about half
   • It stayed about the same

10. Arctic summer (model data)

    Year	Sea ice (million km²)	Sunlight absorbed (units)
    1980	7.8	100
    2020	3.9	125

11. 9.

    Which pair of changes in the table fits the ice-albedo loop, by Zee's reading?

    • More ice in 2020 than in 1980
    • Less ice and more sunlight absorbed
    • Less ice, so the loop must be negative
    • Less ice and less sunlight absorbed

12. Room temperature (model data)

    Hour	Temperature (°C)
    1	18
    2	21
    3	19
    4	21
    5	20

13. 10.

    A thermostat is set to 20 °C. What does the table show the negative loop doing, by Esme's reading?

    • Keeping the room near 20 °C
    • Making the room colder than the setting each hour
    • Driving the room down toward 0 °C
    • Making the room climb higher and higher