The key to the success of tasks in promoting L2 is adopting a proper ordering of tasks. This research was done in pursuit of achieving two goals by utilizing Robinson’s (2010) SSARC (stabilize, simplify, automatize, reconstruct, and complexify) model. The first goal included probing the power of executing the non-complex without spatial reasoning and single listening task and the complex without spatial reasoning and dual listening task ahead of the high-complex spatial reasoning and dual listening task in executing the high-complex spatial reasoning and dual task. Probing the agreement between hypothetically defined task complexity and students’ thoughts on task difficulty was the second goal. To achieve its goals, this research adopted the relative comparison group and correlational designs. Participants of this research were thirty-two female undergraduate students from a non-profit university in Tehran. They were put into high-proficiency groups based on how they did the Oxford Placement Test. Participants of group one executed the high-complex task as the last task in non-complex, complex, and high-complex order and then gave their view of the difficulty level of tasks, while group two participants executed the same task as the first one. The results of the independent samples t-test, one sample t-test, and Spearman’s rho correlation disapproved the statistically significant power of executing preceding lower-complexity tasks in participants’ performance on the high-complex listening comprehension task and the agreement between the way participants think of task difficulty and task complexity has been defined theoretically. Accordingly, executing non-complex and complex listening tasks ahead of the high-complex listening task is not an instrumental means for forwarding how to execute the high-complex tasks and participants’ view of task difficulty cannot be a proper benchmark for determining the cognitive complexity of tasks. What was found by this research is instrumental to the selection and ordering of tasks for L2 classes and learners. Manuscript profile