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 grows the melting: a positive feedback
   • It is negative, since more melting is bad
2. 2.

   A home heater turns on when the room cools and off when it warms. What kind of loop is this, by Bo's reading?

   • Positive, since it is a helpful loop
   • Negative: it keeps the room near one setting
   • Not a loop; the heater just runs
   • Positive: the room gets warmer and warmer
3. 3.

   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, since sweating is good for you
   • Negative: it makes the body colder than before the run
   • Positive: getting hot makes you hotter
4. 4.

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

   • They absorb the same amount
   • Open ocean
   • Sea ice, since it is colder
   • Sea ice, since it reflects more
5. 5.

   Fresh white snow, dark ocean water, a black parking lot and a dark green forest. Which surface has the highest albedo, reflecting the most sunlight, by Luz's reading?

   • Fresh white snow
   • Dark ocean water
   • A dark green forest
   • A black parking lot
6. 6.

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

   • It absorbs 60% and reflects 40%
   • It reflects 6% of sunlight
   • It reflects 60% and absorbs 40%
   • It is 60% ice
7. 7.

   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 ice is good for the planet
   • +, since ice absorbs more sunlight
   • −: more ice, less sunlight absorbed
   • +, since both of them change
8. 8.

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

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

9. Read this first

   Arctic summer (model data)

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

10. 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 and less sunlight absorbed
    • Less ice, so the loop must be negative

11. Room temperature (model data)

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

12. 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 climb higher and higher
    • Driving the room down toward 0 °C
    • Making the room colder than the setting each hour