WISCONSIN
Wisconsin State Legislature
http://www.legis.state.wi.us/
On or before October 15, each "administrator" of a home-based private education program must submit, on forms provided by the department of public instruction, a statement of the home-school's enrollment on the third Friday of September. The form is one page and on it you must state that the program of instruction is provided by the child's parent or guardian or by a person designated by the parent or guardian; that the primary purpose of the program is to provide private or religious based education; that the program is privately controlled, provides a minimum of 875 hours of instruction each year, provides a sequentially progressive curriculum of fundamental instruction in six mandated subject areas; and that the program is not operated or instituted for the purpose of avoiding or circumventing the compulsory school attendance requirement.
The form states that they don't approve or disapprove your curriculum and they suggest you keep a record of your activities and the time spent on them.
There are no testing requirements.