PBS Teachers™

Multimedia resources & professional development for America's preK-12 educators.

Answers

What We Do Adds Up

1. 30.8 pounds of garbage a week
2. 22.72 or 23 days to generate 100 pounds of garbage.
3. On average, 1606 pounds of garbage are thrown away in a year.
4. You have probably contributed a ton of garbage. On average, it takes 454.54 days, which is about 1 year and 90 days or 1 year and 3 months.
5. It takes about 5 years for a person to create 4 tons or 8,000 pounds of garbage?
6. Answers will vary with the ages of students.
7. Answers will vary from county to county.
8. Answers will vary from state to state.
9. Using the projected January 1, 1998 population for the U.S. of 268,922,000, the people in the U.S. will throw away approximately 431,888,732,000 pounds of trash this year. Answers may vary if different population estimates were used.
10. At $20 per ton of garbage, it would cost $4,318,887,320 to place 431,888,732,000 pounds of trash in a landfill. Answers may vary if different population estimates were used.

A Little Recycling Can Go A Long Way

1. Answers will vary depending on the number of students in class.
2. Answers will vary depending on the number of students in class.
3. Answers will vary depending on the number of students in school.
4. Answers will vary depending on the number of students in school.
5. Approximately 76.2 million tons of paper were produced in the U.S. mills in 1996.
6. The average person is using less paper in 1996 than in 1986. On average, each person accounted for approximately 575 pounds of paper in l996.
7. Answers will vary among schools. One way to calculate this is to find the total number of boxes of paper the school orders. Weigh a box of paper and multiply to get the total weight of paper. Divide the total weight by the number of people in your school to get the amount of paper per person.
8. Answers will vary from school to school depending on recycling programs and paper use.

Population Simulation With M&Ms

1. Answers will vary among groups.
2. For each group, this number will be around half of their total.
3. Charts will vary among groups.
4. Sentences will vary. The following are possible sentences:
Each time the number of fish get smaller.
We lose about half our fish each turn.
Half is about right because there is only an "M" on one side of the candy.
5. Sentences will vary. Students should recognize that the pattern would be the same, it would just start with larger number.
6. No answer required.
7. Answers will vary among groups. Possible answers are 2, 3, or 4.
8. Answers will vary among groups.
9. Sentences will vary. The following are possible sentences:
The population continues to get larger and larger.
The population grows by about half each year.
10. The population would just continue to grow because about half of the fish would generate another fish.

Adventures With The Fish Pond: Population Modeling

1. Sentences will vary. One possible sentence is: "Next yearís fish population will be smaller than last yearís." A more descriptive sentience is: "Next yearís fish population will be one half of this yearís fish population."
2. Equations will vary. Possible equations are:
NEXT = NOW - .5 NOW
NEXT = .5 NOW
NEXT = NOW/2
3. If there are 80 fish the first year, there will be 40 fish the next year.
4. There are will be 20 fish the following year.
5. There are will be 10 fish the following year.
6. No answer required.
7. No answer required.
8. Students should get 40 on their calculator.
9. No answer required.
10. It is exactly 5 on year four. So it will take five years for the population to be below 5.
11. It will take seven years for a population of size 1,000 to fall below 10.
12. It will take eight years for a population of size 2,000 to fall below 10.
13. It will take ten years for a population of size 8,000 to fall below 10. After two years, a population of 8,000 would be down to exactly 2,000, and we know it takes eight years for a population of 2,000 to fall below 10.