With the advent of technology, many have shown the benefits of data-driven learning (DDL), i.e., using corpus data to improve second language writing accuracy. Despite the increase in DDL studies, some gaps still exist. Previous studies tended to examine learners’ corpus use without looking into other correction methods (e.g., Google, dictionaries, or personal knowledge). Little has been documented regarding whether an error was really corrected by corpus concordancing or if it was based on students’ linguistic knowledge. Moreover, although prior research has indicated that shorter class periods would be enough for basic corpus training, how learners are involved in DDL for error correction over an extended period of time has rarely been documented. This study aims to bridge the gaps by examining not only students’ use of corpus tools, but also how they use other methods for error correction over an 18-week semester. Four corpus tools were introduced: Corpus of Contemporary American English, Just the Word, Netspeak, and Google(targeting the use of quotation marks “ ”). Adopting a mixed-method approach, data sources included students’ essay drafts and revision logs, retrospective interviews, as well as a questionnaire. The findings showed that the majority of the corrections were based on learner knowledge, while corpus-based corrections remained limited. Nevertheless, the students were able to draw on various reference resources including the four tools for error correction, and 70% of marked errors were corrected successfully. Qualitative analysis of the survey and interview data revealed that the participants perceived DDL for error correction as beneficial, although some seemed to have difficulties using these tools. Among the tools, Netspeakand Googlewith quotation marks were consulted more frequently because they provide easy access to search results with the frequency of the target word/phrase, while COCAappeared to be more complicated. This paper concludes with a discussion of pedagogical implications and limitations of the study.