Abstract
Nowadays Task Based Language Instruction is considered as one of the widely used approaches in foreign language teaching. Scaffolding, support from teachers to help learners accomplish tasks that can not be completed independently, gradually reduces as students gain skills and confidence, is effective way of improving reading comprehension skills in language classrooms. This study investigates the effectiveness of TBLI scaffolding as a strategy for improving reading comprehension among low and high proficiency students. Quasi-experimental design was employed to compare the effect of it in both proficiency levels before and after exposure to TBLI interventions. Data were collected through pretest, posttest and lesson observations from 30 students of 10th grade in local school. Statistical analyses, including paired-sample and independent-sample t-tests, to evaluate the significance of within and between group differences. Experiment lasted for 6 weeks, where students had 18 academic hours of learning the English language. The findings reveal that TBLI improves reading comprehension skills of both groups, however low language proficiency students gain more advantages in comparison with higher level students. TBLT has great value in supporting learners with limited linguistic resources by making comprehension more accessible. Conversely, high proficiency students, who already feel comfortable demonstrating independent work and complex tasks, which is the main purpose of scaffolding, benefit less from this approach. Key words: TBLI, scaffolding, reading comprehension, language proficiency.