LEP is an acronym which stands for Limited English Proficiency. Hence, a LEP student is considered an English Language Learner or ELL.

Liying Cheng has written:

'English language assessment and the Chinese learner' -- subject(s): English language, Study and teaching, Chinese speakers, Ability testing

The L1 will help the learner acquire the L2 language, but the key here is that the learner has to be literate in the L1 before it can be used as a foundation for the L2. If the learner is not literate the teacher can not use the L1 and has to start from the basics for the L2.

There are four main things that any language learner need-Motivation, Good resources, Time, Discipline.

a naturalistic learner is someone who learns the language at the same time as learning to communicate in it

source: Second Language Acquisition-Rod Ellis