This study sets out to address the call for more ecologically valid research within the field of second language acquisition (SLA) (e.g., Spada, 2015). A considerable body of research has investigated the effects of input spacing, that is the amount of time between learning episodes, on the learning of foreign language (L2) vocabulary. This body of research has overwhelmingly demonstrated that more distributed conditions lead to better learning and retention than when there is a short gap between learning episodes (Carpenter, 2017) However, as the vast majority of this body of research has been carried out in laboratory settings with adult learners, the degree that these results necessarily generalize to authentic classroom contexts is questionable. The present study attempts to address this gap in the literature by examining the learning of L2 vocabulary within an authentic L2 learning context in an elementary school context in Hong Kong.This study followed a pretest-delayed posttest design to examine the effects on input spacing on the acquisition of L2 vocabulary, specifically English adjectives. Across four primary classrooms, participants (N=52, L1 Cantonese) were taught 20 English adjectives by their normal classroom instructors over two learning sessions. Half of these adjectives were taught following a spaced-short schedule (1 day between learning episodes), the other ten adjectives following a spaced-long schedule (8 days between learning sessions). A multiple choice post-test was administered following a 4 week delay. In contrast to the findings from previous, laboratory-based research, the results of this study found a significant advantage for the spaced-short condition, thus suggesting that previous findings of lag effects in L2 vocabulary learning might not be robust to the variabilities present in authentic learning environments. The results will be discussed further in light of previous research into distributed practice effects and theories of bilingual

This study examined the optimal learning schedule for second language vocabulary within an authentic classroom setting in Hong Kong. Following a pretest, treatment, delayed posttest design, fifty-two primary school students (Cantonese first language) studied 20 English adjectives over two learning episodes under spaced-short (1-day interval) or spaced-long (8-day interval) learning conditions. The spacing of the vocabulary items was manipulated within-participants, and learning was assessed on a multiple-choice posttest, administered following a four-week delay. In contrast to previous laboratory-based findings, the results here indicated superior learning of the items presented under the spaced-short format, suggesting that lag effects might be attenuated by age, learning context and teaching procedure. Copyright ©Sage Publications Ltd.