Skeptics would say that learning a language is impossible to learn well online. They would also name dozens of reasons, and one of them would surely be the writing practice.
How can students learn to write if a tutor is not sitting next to them and showing them directly?
No matter the language you are teaching and its writing rules, writing is possible on the platform. Moreover, there is no difference in writing online on a computer or writing on paper.
While explaining writing rules, the tutor can write them in the chatbox.
While practicing, the student also can write in the chatbox. Simple as that.
In cases when a student practices writing, a tutor dictates, and a student writes. After finishing, the tutor checks writing and can explain writing errors if there are any.
Practicing writing is recommended as often as possible. This way, a student can better and faster learn to write, learn new words, and after some time, have an inner feeling when hear some unfamiliar words to write or spell them.
The tutor may not sit next to a student literally, but he/she sits virtually. So, whether a student writes on real paper or virtual paper, the result is the same. That result is successfully learned writing and vocabulary.