Although research on the effect of etymological elaboration (provision of information about a word’s origin and background in instruction) on L2 idiom acquisition has showed that it is a useful mnemonic approach that can help L2 learners retain target idioms (Boers, Demecheleer, Eyckmans, 2000, 2004, 2007 ), most previous studies were conducted in a pencil and paper based situation and few made use of computer technology and internet as a vehicle to deliver such an instructional approach. With a wide use of web-based learning tools (Moodle, WebCT, etc) in American universities, Research data on the online application of etymological elaboration and its effect are far from sufficient compared with those from classroom experiments. Therefore, a study on the actual effect of etymological elaboration in an online learning environment is necessary to supplement previous studies by providing more information about the effect of such an instructional approach in different media.

This current study, grounded on cognitive learning theories and web-based learning framework, was designed in an online, autonomous learning manner. Specifically, it intended to measure L2 learners’ acquisition and retention of target idioms through two different instructional approaches, etymological elaboration and traditional rote learning, in an online learning management system (LMS), WebCT. Three research questions were addressed in the study: (1) Can online learning contribute to students’ L2 idiom acquisition? (2) Can an etymological elaboration approach be effective in facilitating students’ L2 idiom retention in an online environment? (3) What are the strengths and drawbacks of learning idioms online according to learners’ learning experience? Seventy Chinese sophomores in Anhui university, China, participated in the study and their productive and receptive knowledge of target idioms were measured through data collected from pretests, post-tests, delayed post-tests. In addition, an online questionnaire survey was distributed to the participants to look into their actual online learning experience.

Results of the study indicated that while online learning was an effective way to facilitate L2 idiom acquisition for both instructional approaches, etymological elaboration did not produce an overall significant effect on the retention of target idioms over traditional rote learning approach except in the retention test of productive knowledge of target idioms.