On the last exercise of world 6, rewrite the highlight, "cw" leaves the "a" at the end of the line. Both "c$" and "C" work. I didn't know about "C" until I read

On the last exercise of world 6, rewrite the highlight, "cw" leaves the "a" at the end of the line. Both "c$" and "C" work. I didn't know about "C" until I read the web page - I've been using c$ for that.