For gifted and talented programs, some teachers have begun implementing or requesting non-verbal testing, especially for early childhood students, so that language and speech development do not block children who are gifted in other ways from entering the program. Ask your campus gifted and talented teacher what the process is to enter the program and what type of entrance exam the students will be given. Sometimes other forms of evidence can be submitted in the student's favor as well. You can also suggest or research tests that demonstrate student ability through multiple intelligences instead of standard forms of testing. In the classroom, you can give open-ended tests which allow for student expression and interpretation of knowledge instead of rote memorization and allow for students to justify their ideas and answers. Using these techniques will help to avoid and eliminate cultural bias in testing.
Finally, when standardized testing comes around, be an advocate by noticing questions or topics which reveal obvious cultural bias and report them to your school official or testing agency. Test writers may not be as aware of these intricacies as the teachers who interact with students every day. If enough people speak up, changes might be made.