Hamid Rahmani Sangani - PH.D of Applied Linguistics, Velayat University, Iranshahr, Iran
Ehsan Shahbazi Tochahi - MA Student of Applied Linguistics, Velayat University, Iranshahr, Iran

The purpose of present article is to demonstrate the impact of online android application called WhatsApp as a dynamic assessment instrument on the learners‟ development of grammatical features. To do so, 22 intermediate learners who were studying in Shokoh institute in Rasht and were at the same level of English proficiency were selected through an English proficiency test on grammar. Then, they were equally assigned into the experimental group and the control group. The experimental group was dynamically assessed through WhatsApp application environment, and the control group was dynamically assessed in a usual class without any software. Both contexts were observed by the researcher. Finally, a post test was conducted to see the student development from pre-test to post-test. The results showed that the experimental group had a better development of grammatical features than the control group did. It was also observed that the experimental group was more motivated by the process

Dynamic assessment, WhatsApp, interventionist