While task-based instruction is considered as the most effective way to learn a language, it is oversimplified on various grounds. Among the variables that determine the effectiveness of a certain task in language learning are the opportunities it creates for negotiation of meaning. Interactional theories hold that language learning is an outcome of participating in discourse, in particular face to face interaction. Interactional modifications through negotiation for meaning can have a positive effect on the quality of learners' immediate production. It is through negotiation of meaning and being in interaction in task based education that learners develop language proficiency. Tasks which stimulate negotiation, comprehensible input and feedback, and opportunities for pushing learners to reformulate their language are the ones that work best for acquisition. It is widely argued that different types of tasks facilitate the acquisition of communicative language to different degrees as they provide different contexts for the occurrence of negotiation of meaning.Therefore, exploring the tasks that promote more units of negotiation of meaning is highly significant.