Bilingual students are sometimes difficult to detect. I am not referring to the person who has just arrived in this country and has a distinct accent if/when they speak English. I am, though, referring to the student who comes from a home where another language is spoken. They may appear to "speak" English without an accent.
They seem to be English speakers, but they do have a impairment that needs to be recognized and addressed. They have learned some concepts in English and some in their native language. They may not say anything, but remain silent. In a regular classroom, one might miss the look on their face or the body language that shows they do not understand. For example, I was discussing parts of a farm while an English speaking kindergartener was coloring. I realized he did not know the name "farm", so he stopped listening to me. He was trying to make some sense of the word. I recognized the body language and said the word "farm" in Spanish, "la finca". There was instant recognition. He proceeded to tell me all about his grandfather's horse farm in Puerto Rico.
This happens every day in any classroom where one may include bilingual students. You must be sensitive to this and prepare your "antenna" to be on alert for this and catch it as early as possible so learning can continue. Thus, you and the child will be successful in the learning process.