I'm trying to come up with a good thesis statement on child abuse, then I have to determine whether it's a claim of fact, definition, value, cause, or policy... any suggestions?

An idea maybe to check with the Ministry of Children and Family, depending on where you live.

Have you even done any research on your own yet?

Tennyson Center for Children - Childabuse.org

Child Abuse: Statistics, Research, and Resources

MedlinePlus: Child Abuse

Child Abuse Prevention Network

A good thesis statement will present one argument and not try and take on all the factors. As the rest of your paper, you have to present material/statistics/documentation to support your opening statement.