Research on number sense presents contradictory arguments and results regarding the effects of context-based tasks and activities on students' number sense. The aim of this study was to examine fourth-grade elementary school students' number sense as they solve context-based (CB) and non-context-based (NCB) items. A survey design was employed and data collected using CB and NCB tests for this purpose. The results showed that students were more successful on NCB test compared to the CB test. Students performed best on the problems related to the "using a reference point" component of number sense, while they performed worst on the "understanding of the number size" component. The majority of students used rule-based strategies (RBSs) for both CB and NCB tests. Interviews with students who solved CB items using RBSs showed that students were able to recognize and use number sense-based strategies (NSBSs) to some degree when they were asked for alternative solution methods. The variability found in students' recognition and use of number sense seem to depend on such factors as the lack of number sense, preference to RBS, task structure (e.g. involving visual representations and easy numbers), and task requirements (e.g. asking for estimation or comparison vs. exact answer, requiring additional adjustments on reference points).