Decisions

Subject Area
Math

Activity Overview
You have been commissioned to create a biosphere (a zone of terrestrial life including water, land, and atmosphere) in your back yard. If the mixture of plants to human life is 7:1, how many plants would you need to keep this proportional balance? The number of humans is 13.

Objective
Students will calculate and estimate the number of plants it will take to create a harmonious biosphere.

Materials
paper and pencil
calculator
math journal

Activity Outline
Discuss the concept of estimation. If necessary, discuss how to use a calculator.
Have students:
1. Estimate how many plants would be needed and write those totals down in the journals.
2. Estimate how many humans are needed. What if the mixture was 28 plants? 14 plants? 33 plants?
3. Reflect in their journals their estimates, actual answers, and why would their answers might be important for people in the present time.
4. Check with another person to see if their answers are similar. Why or why not?
5. Reflect in their journals and with a partner whether or not a balance of seven plants to one human seems like a nice mix for their biosphere.

Assessment Options
Check the accuracy of their answers in their journals.

Standards and Benchmarks
Standard 1: Uses a variety of strategies in the problem-solving process
1. Understands how to break a complex problem into simpler parts or use a similar problem type to solve a problem
5. Represents problem situations in and translates among oral, written, concrete, pictorial, and graphical forms
6.Generalizes from a pattern of observations made in particular cases, makes conjectures, and provides supporting arguments for these conjectures (i.e., uses inductive reasoning)
7. Constructs informal logical arguments to justify reasoning processes and methods of solutions to problems (i.e., uses informal deductive methods)


Standard 3: Uses the basic and advanced procedures while performing the processes of computation
3. Selects and uses the appropriate computational methods (e.g., mental, paper and pencil, calculator, computer)
7. Knows when an estimate is more appropriate than an exact answer for a variety of problem situations
8. Understand the concepts of ratio, proportion, and percent and the relationships among them

Standard 4: Understands and applies basic and advanced properties of the concepts of measurement
8. Selects and uses appropriate estimation techniques (e.g., overestimate, underestimate, range of estimates) to solve real world problems

Standard 7: Understands and applies basic and advanced concepts of probability
3. Understands how predictions are based on data and probabilities (e.g., the difference between predictions based on theoretical probabilities and experimental probabilities)

Standard 8: Understands and applies basic and advanced properties of functions and algebra
11. Understand the properties of arithmetic and geometric sequences (i.e., linear and experimental patterns)

Standard 9: Understands the general nature and uses of mathematics
1. Understands that mathematics has been helpful in practical ways for many centuries
2. Understands that mathematics often represent real things using abstract ideas like numbers or lines; they work with these abstractions to learn about the things they represent