This research study tends to evaluate the efficaciousness and usability of a Vocabulary Learning And Strategy Teaching Web-App (VLASTWA) -- a customised and targeted web-app for (1) teaching the KeyWord Method (KWM) which is a widely investigated vocabulary learning strategy, and (2) facilitating new vocabulary learning via KWM. In this experimental study, with a between/within design, native Persian participants (n=160, age:18-60) learnt to use KWM, applied it in acquiring 22 new words, and tested this newly learnt vocabulary immediate (T1)/delayed (T2) recall. The effectiveness of the use of KWM taught within the web-app and the traditional Pen and Paper (P&P) in the experimental groups were compared with the control app and P&P groups via immediate/delayed recall of learnt vocabulary. The results suggest VLASTWA was efficient for learning new vocabulary while highlighting how meaningful and interactive it can be in accompanying and enriching Foreign Language (FL) vocabulary learning. [For the complete volume, "CALL for Widening Participation: Short Papers from EUROCALL 2020 (28th, Online, August 20-21, 2020)," see ED610330.]