scribble away (at something)
To work hard and hastily writing something down, especially by hand. The students were all scribbling away so intensely that they didn't even notice their teacher leave the room. I could sit in a coffee shop all day scribbling away at my novel, but they don't like it when I loiter there for more than a few hours at a time.
scribble away (at something)
to write hard and fast at some task. He scribbled away at his notes as the lecturer droned on. Jane sat in the library scribbling away.