It is not just scrolling, it is the fill-in-the-blanks culture

Use phonetic method, which always works. Forget about Whole language nonsense. Get Why Johnny Can’t Read by Rudolf Flesch, it has twenty of thirty pages of instructions, really simple. Forget about online websites.

As for pen and paper vs. scrolling, the problem is bigger. It is, in fact, blank pen and paper vs. pre-filled worksheets, be it paper worksheets or on-screen. Worksheets are evil. Use plain paper as much as you can. Use squared paper for everything except for cursive writing.