Teachers often sent tests with the students. I noticed how difficult tests are for these students and I asked the ESL teacher about this concern. Multiple choice tests are familiar to us because we have taken them all our lives. She explained to me that ESL students often do not understand the format of our tests. The problem may be in our design.
Language barriers are obvious, but try implementing other types of assessments.
Talk with the students and offer to use a method they are accustomed to or that they at least understand. Cultures are different, including the culture of schools.