Ask Testy for writing practice on his own page and he opens a writing studio inside the conversation. There is no button called Writing Studio to hunt for: Testy puts it there when it is wanted.
Writing the piece
The studio shows the genre, the prompt as its heading, a word counter against a target and a timer that can be started and paused. The writing area is plain and spell checked. Typing costs nothing and is saved as the student goes, and Testy stays quiet while they write: he reads the whole piece when he is asked, not sentence by sentence.
Marking it
Mark it is the button at the bottom, and pressing it is the one action that uses an allowance. Under the minimum length the button explains that a few more words are needed first. While Testy reads, the screen says what he is doing.
The feedback
Two things come back. A card headed Testy has marked your piece gives a headline, a band for each aspect (Ideas, Structure, Sentences, Vocabulary and Conventions), then What worked and Next steps. The card can be hidden and brought back.
At the same time, lines in the text are underlined and a note is pinned in the margin beside each one. A note is tabbed Fix this, Make it stronger, An idea or This works, and shows the student's own words and, where Testy has one, a suggested wording. Use this applies the suggestion, Not this time sets it aside, and an applied suggestion can be undone the usual way.
Marking it again
Marking the same piece again without changing anything is free. Marking it after an edit is a fresh read and uses one more activity, which is the point: the studio is built for a second draft.
This is not the same as a writing test
A writing task inside a marked practice paper is scored work on a real paper. The studio is coaching. See Online Practice Tests for marked writing.