The second half of the school year starts in couple of weeks. Students will return rested and ready to tackle the new year. Teachers will encourage students to see January as a new beginning. Last semester is history:) This approach is generally very effective in building self-confidence in ELLs who tend to have double the work load in that they are trying to develop English skills while attempting to access content.
A skill, which addresses both needs, is being able to dissect vocabulary words to find meaning. This can be done via analyzing word parts (affixes). If the ELLs are romance language speakers (Spanish, French, Italian, Portuguese, Romanian), they can use common Latin affixes to make sense of unfamiliar words. When teachers bring in this and the use of cognates (ex. nacion/nation), barriers to meaning drop away. Greek roots are also here (including a section on mythology vocabulary). A special feature of VOCABULARY UNIVERSITY is that it addresses word roots in a variety of activities--puzzles, quizzes, synonyms, true/false, etc. Another plus about this site is that it covers key vocabulary from all the major courses.
A second strength here is that it offers practice for high stakes tests such as SAT and ACT. If teachers have high school ELLs, they might consider letting ELLs (and others) practice the vocabulary they will need to do well on those high pressure tests.
I think your students will enjoy this site either as a class working with the teacher or an individual at his/her computer in the school computer lab.
ELL TEACHER PROS