The Big Five Personality Test
This personality test is a great tool for introducing the concept of personality. The site has a brief questionnaire that users can take to assess their personality based on the Big Five factors of openness, conscientiousness, extroversion, agreeableness, and neuroticism. After submitting this test, users see the results of their test and are taught about the different factors of personality that formulate the results. Also the results are printable and the user has the option of saving the link to their personal results as well.
For an example of the results page, please visit an example test: