It teaches a 3-step method: split it, name the pattern and read it back. Along the way you get worked examples with the key words marked, before-and-after fixes that show why the first version loses marks, a one-page visual summary, word cards with meanings and examples (accommodation, necessary, separate and environment), a quick check to test yourself and a recap of the rules to remember. Each card holds one idea, so you can read it on a phone between practice sessions.
Reading it online is free: create a free BandLadder account and the whole lesson opens in our study reader, on the web and in the app. Downloading the PDF to keep needs a plan; the free reader has every card.