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An Elementary School Science Teacher Decided to Liven Up the Classroom

question 27

Multiple Choice

An elementary school science teacher decided to liven up the classroom with a saltwater aquarium. Knowing that saltwater aquaria can be quite a hassle, the teacher proceeded stepwise. First, the teacher conditioned the water. Next, the teacher decided to stock the tank with various marine invertebrates, including a polychaete, a siliceous sponge, several bivalves, a shrimp, several sea anemones of different types, a colonial hydra, a few coral species, an ectoproct, a sea star, and several herbivorous gastropod varieties. Lastly, she added some vertebrates-a parrotfish and a clownfish. She arranged for daily feedings of copepods and feeder fish.
-One day, little Tommy (a student in an undersupervised class of 40 fifth graders) got the urge to pet Nemo (the clownfish) , who was swimming among the waving petals of a pretty underwater "flower" that had a big hole in the midst of the petals. Tommy giggled upon finding that these petals felt sticky. A few hours later, Tommy was in the nurse's office with nausea and cramps. Microscopic examination of his fingers would probably have revealed the presence of

Definitions:

Public Good

A product or service that is non-excludable and non-rivalrous, meaning its consumption by one individual does not reduce its availability to others.

Collective Willingness

The aggregated preference or desire of a group of individuals to support or buy into a particular idea, policy, or product.

Marginal Cost

The boost in complete costs associated with creating one more unit of a product or service.

Private Good

A product that is excludable and rival in consumption, meaning its use is limited to the purchaser and it cannot be shared without diminishing availability to others.