Ms. Spencer, a fifth-grade teacher, gives a blue plastic sta…

Ms. Spencer, a fifth-grade teacher, gives a blue plastic star to each student who achieves an “A” on a math or spelling test. At the end of the semester, students can even exchange their stars for prizes. Ms. Spencer’s strategy best illustrates an application of:

When Cassandra was asked to sell tickets to a barbecue for h…

When Cassandra was asked to sell tickets to a barbecue for her school club, she was at first upset because of her own vegetarian lifestyle and belief that animals should not be killed for food. However, Cassandra was soon able to see that because most people aren’t vegetarians, and the purpose of the barbecue is to raise money for the club, it made the most sense to cook and sell meat at the event; besides, she wouldn’t personally have to eat any meat. This change in Cassandra’s attitude is best explained by: