Purpose: The purpose of this study was to compare the relative effectiveness of three Sight Word Instructions
with Augmentative and Alternative Communication(AAC) for students with severe disabilities. Method: For this,
single-subject research targeting a middle school student with severe disability through alternating treatments
design(ATD) was used to analyze define the effects on the word recognition. The experiment was conducted
follows: preparation and pre-education, baseline, intervention, and the post-intervention baseline. During the
intervention, 3 sight word teaching strategies (ie., speech generating device(SGD) based on smart device, picture
communication symbol(PCS) card, & multimedia learning) were conducted 10 times each to the target student.
In the post-intervention baseline, strategy with SGD based on smart device which has been proved to be most
effective was performed. Results: Comparing 3 strategies of sight word Instructions, we concluded that the way
of using SGD based on smart device is the most effective one. Conclusion: This results mean that the strategy
through SGD based on smart device is the most effective way of sight word Instructions. Therefore, this study
discuss about the educational implications and limits of the results.