Teachers can demonstrate how easy in-groups and out-groups form by dividing students into two groups based on something as simple as whether they are wearing athletic shoes. Have each group (athletic shoe wearers and non-athletic shoe wearers) sit together and discuss the reason the other group is wearing athletic shoes or not wearing athletic shoes. There is a tendency for comments to become more derogatory as the discussion progresses -- forming an in-group and out-group.
The "Prisoner's Dilemma Game" demonstrates cooperation and competition. This game is based on a situation in which two people are arrested for a crime and immediately separated. Each prisoner is told if he defects (competes) by confessing and testifying against his co-criminal, his sentence will be reduced. If neither defect (cooperate), they will both get a short sentence. However, if both deflect, they will both get long sentences. Divide students into groups of three with the middle person being the scorekeeper and the other two game players. The players cannot communicate but must decide whether to cooperate or compete on each of 10 trials and handing their choice on paper to the scorekeeper. Play the game with points instead of sentences. For example, tell students if they defect (compete) and their colleague does not, they will get 12 points and colleague will get minus 6, but if both deflect each will get 0 points. If neither deflects (they cooperate with each other) they will each get 6 points.
This activity demonstrates the concept that people think similar others have attitudes similar to them. The teacher must develop a simple questionnaire, perhaps on political candidates for an election (for example, "I think Sarah Palin will be the Republican candidate for president in the next election"). The questionnaire may be as short as five items. Ask the students to respond individually to the questionnaire on a five-point scale from 1, indicating strongly disagree to 5, indicating strongly agree. Then, ask them to estimate the percentage of students who share their opinion on each item. Finally, ask students for a show of hands for responses on each item. Students will overestimate how many other students (people similar to themselves) share their opinions.
People tend to attribute their own behavior to the situation and others' behavior to personality characteristics -- this is the fundamental attribution error. Divide students into pairs, and ask them to interview each other to determine their personalities. After a few minutes, give them a questionnaire to complete about their new friend. The questionnaire should list about 10 (all neural or positive) characteristics (for example, "outspoken" or "cautious") plus "depends on situation." Ask each student to complete the questionnaire about her friend. Then, ask the students to complete the same questionnaire for themselves. Have the students count the number of "depends on situation" for self and friend. Most people choose "depends on situation" more often for themselves than for friend.