Students learning English as a second language may not know enough of the language to be conversational at first. This discourages some students who believe that their inability to form longer, more complex sentences and to answer questions in English is their fault. Using L1 in these cases makes it easier for teachers to encourage students and to give them hints when they are conversing in English. Encouragement and hints may not be as effective if they are given only in English and the student does not fully understand what is being said.
ESL students have assignments and assessments just like students in any other class. They must pass examinations and show they are capable and know enough English to pass the course. If a students doesn't understand the directions on a test or the instructions for an assignment, the chance of performing well for those assessments greatly decreases. By giving the instructions in L1, the teacher increases the probability of ESL students excelling in their English assessments.
Because the United States may be very different from some of the places that ESL students immigrate from, it is often important for them to be able to understand American culture. This will help them to speak the language with more confidence and to avoid embarrassing conversational situations in the future. At times, explaining American traditions and concepts in L1 makes it easier for students to grasp the cultural concepts.
Because many ESL students have been plunged into a completely new environment with people they cannot understand who in turn cannot understand them, it is important for students to have a place where they can ask questions about English and the U.S. and have them answered without ridicule or embarrassment. Though it is necessary for the ESL students to speak and understand English, it is also important for them to have a time and place where they can relax and be themselves. Using L1, even if only at certain times during an ESL class, provides them with such an opportunity.