Births, deaths, immigration and emigration
Grade 9 Science Worksheet - Building Confidence
Circle the best answer.
Read this first
Frogs in one pond in one year (model data)
count frogs births 14 deaths 6 immigrants (moved in) 3 emigrants (moved out) 2 Ari reads the model data for frogs in one pond. What is the change in the number of frogs?
- +15: (14 + 6) − (3 + 2), deaths put with the gains
- +9: (14 + 3) − (6 + 2)
- +17: 14 births + 3 immigrants, with no losses counted
- +8: 14 births − 6 deaths, with no moves counted
Turtles on one pond island in one year (model data)
count turtles births 8 deaths 5 immigrants (moved in) 2 emigrants (moved out) 7 Bo reads the model data for turtles on one pond island. What is the change in the number of turtles?
- +10: 8 births + 2 immigrants, with no losses counted
- −2: (8 + 2) − (5 + 7)
- +3: 8 births − 5 deaths, with no moves counted
- +2: (5 + 7) − (8 + 2), the losses minus the gains
Ducks on one lake in one year (model data)
count ducks births 12 deaths 9 immigrants (moved in) 4 emigrants (moved out) ? change in the number of ducks 0 Esme reads the table. The number of ducks did not change. How many emigrants moved out?
- 7: the losses must match the 16 gained, and 16 − 9 = 7
- 3: 12 births − 9 deaths, with the arrivals left out
- 16: 12 births + 4 immigrants, the gains and not the moves out
- 5: 9 deaths − 4 immigrants, one loss and one gain mixed
Birds in one wood (model data)
year births deaths immigrants emigrants 2022 16 10 4 4 2023 24 14 3 5 2024 18 6 7 2 2025 20 6 0 12 Jun reads the table of birds in one wood. Immigrants moved in; emigrants moved out. In which year did the number of birds grow the most?
- 2023: the most births, 24, in any year
- 2024: a gain of 17 birds
- 2025: the biggest births minus deaths, 14
- 2022: the first row of the table, with 16 births
Bees on one hillside (model data)
year births deaths immigrants emigrants 2021 30 18 2 8 2022 22 20 6 8 2023 26 26 4 9 2024 14 9 1 3 Luz reads the table of bees on one hillside. Immigrants moved in; emigrants moved out. In which year did the number of bees stay the same?
- 2024: the fewest births, 14, so the count held steady
- 2023: births and deaths are both 26, so nothing changed
- 2022: the gains and the losses are both 28
- 2021: the most births, 30, so the count held steady
Milo reads the graph. How many seedlings are in the plot at year 4?
- 90 seedlings: the height of the line above year 5
- 65 seedlings: the height of the line above year 3
- 80 seedlings: the height of the line above year 4
- 4 seedlings: the year, read as the count
Noah reads the graph. Between which two years did the number of ducks fall the most?
- Year 2 to year 3, a fall of 8
- Year 3 to year 4, a fall of 16
- Year 5 to year 6, a fall of 8
- Year 0 to year 1, a fall of 8
Pia reads the graph. What is the change in the number of frogs from year 2 to year 5?
- +70 frogs: the count at year 5
- +30 frogs: the count at year 2
- +40 frogs: 70 − 30
- +3 frogs: year 5 − year 2
Two plots of plants (model data)
plot plants area (square meters) A 90 30 B 60 10 Tala reads the table. Which plot has the higher density of plants?
- Plot B: 6 plants per square meter, against 3 for plot A
- Plot A: 3 plants per square meter, against 6 for plot B
- Plot A: it has more plants, 90 against 60 in plot B
- Plot A: it has the larger area, 30 against 10 for plot B
Two strips of pond edge (model data)
strip snails area (square meters) X 48 12 Y 48 6 Zee reads the table. Both strips hold 48 snails. Which strip has the higher density?
- Strip Y: 8 snails per square meter, against 4 for strip X
- Strip X: it has the larger area, 12 against 6 for strip Y
- The same: both strips hold 48 snails, so the density is equal
- Strip X: 4 snails per square meter, against 8 for strip Y