1. Host family is the family that provides ‘board and room’, food, etc. for overseas visitors or students. You can find two American examples at http://www.wooster.edu/oisa/hostfam.html (Ohio) or http://www.uwec.edu/Admin/Cie/fsa/host.htm (Wisconsin).
A Canadian site at http://www.cdncollege.bc.ca/hostfam.htm may be a more interesting example because it is an ESL college with an international exchange program.
You can also take a look at http://users.dove.net.au/~johnbaxt/family.html that provides a personal account from the perspectives of an Australian host family. It is a story about an international exchange program NOT associated with a particular college, but rather, fostering international understanding and friendship (The text itself may be a little more difficult for the students to comprehend).
2. Christians are followers of Jesus with whom they have a personal relationship and whom they accept/receive into their lives as God’s son and the way to heaven. They believe that there is one God. Most Christians are members of one of three major groups -- Roman Catholic, Protestant, or Eastern Orthodox.
Christianity has had an enormous influence on Western civilization, especially on art, business, government, and social relations. See http://www.riverpower.org/ for answers to some frequently asked questions about Christianity.
3. Income tax is one of the taxations on individuals and companies. In many countries or regions such as the US and Western Europe income tax is one of the major financial resources of the government. It first appeared in France in 1793. See http://www.law.cornell.edu/topics/income_tax.html for a clear and concise explanation of income tax law as it applies to individuals and businesses in the US.
4. Health insurance is a system for the advance financing of medical expenses by means of fees or taxes paid into a common fund to pay for all or part of health services specified in an insurance policy or law. Health insurance may apply to a limited or broad range of medical services and may provide for full or partial costs of specific services. Benefits may consist of the right to certain medical services or repaying the insured for specified medical costs and may sometimes include income benefits for working time lost owing to sickness or maternity leave. For information and introduction to health insurance in the US, you can visit the website of the Health Insurance Association of America at http://www.hiaa.org, especially the consumer information section at http://www.hiaa.org/consumer/guides.cfm. The latter section contains introductory materials that are ideal for classroom instruction.
