This study explored a way to help Japanese university students write longer essays while maintaining grammatical accuracy. Participants were three groups of students enrolled in a one-year EFL course in consecutive academic years (N = 111), and the number of words they wrote in 30 minutes and the number of errors made per 100 words were compared. To improve the participants’ grammatical accuracy, comprehensive coded feedback (e.g., Bonilla, et al., 2018, 2021; Hartshorn, et al., 2010) and selective metalinguistic explanation (e.g., Bitchener & Knoch, 2010; Sheen, 2007) were provided on the 12 paragraphs/essays they submitted. The first, sixth, and last essays were analyzed to assess their verb tense and mechanical errors. Regarding the length of writing, the first group kept writing about 150 words, the second group was encouraged to increase the length of writing at their own discretion, and the third group was systematically guided to write longer essays by following a prescribed guideline. The ANOVA results showed that the two groups that wrote longer essays significantly outperformed the short-essay group in the length of writing without sacrificing grammatical accuracy. The correlation analyses produced evidence against a possible trade-off between accuracy and fluency (Lambert & Kormos, 2014; Skehan, 2009).

The present study evaluated the effects of a combined form of written corrective feedback (WCF) on English as a foreign language (EFL) students’ writing accuracy. The combined WCF consisted of unfocused error-code WCF and focused metalinguistic explanation. Different forms of WCF were administered to two groups of Japanese EFL students in two consecutive years, and the effects of the feedback were compared based on the number of grammatical errors that the students made before and after receiving feedback. The original version (single combined WCF) provided metalinguistic explanation only once for each of eight target grammatical forms, whereas the intensive version (repeated combined WCF) provided metalinguistic explanation repeatedly. The results showed that combined WCF facilitated the students’ accurate use of the target forms overall, and repeated combined WCF was more effective than single combined WCF, but its efficacy weakened over time. Repeated combined WCF had a positive effect on students’ accurate use of verb tense and the avoidance of informal usage; single combined WCF had a significant effect only on verb tense. Repeated combined WCF also served to reduce the total number of errors, including errors for which no metalinguistic explanation was given, implying that coded WCF had its own contribution to the students’ writing accuracy.