Tests that are administered via written English can often pose a challenge for those whose first language is not English. Not every learner who uses a signed language to communicate will struggle with written English. However, some will, for a variety of reasons which vary from personal educational history, lack of incidental learning, and lack of access to adequate services. It is also important to understand that American Sign Language (ASL) is not simply English in signs. ASL has its own rules of grammar and structure that are not based in English and vary greatly from the rules of the English language.
Having a sign language interpreter during the assessment process is a reasonable accommodation. Most of the time only one interpreter will be present. Interpreters are present to facilitate all instructions prior to the test and to provide interpreting services during the test if needed. Interpreters, ethically, do not provide the learner with any answers to question on the exam. The service provider is available if you have concerns about the presence of an interpreter during assessments.