The level 2 textbook is teaching students the expression how about...? But I think it's slightly misused, and it wouldn't surprise me if other textbooks did the same. Here are the dialogues.
A: How about parking over there?
B: Okay.
A: How about going to the movies?
B: Okay.
As far as I know, How about...? should be used to establish or change the subject within a topic. For example, if someone has already suggested that one make evening plans, then it's okay to use How about to suggest going to the movies as the subject.
A: We should hang out tonight.
B: Yeah, that sounds good.
A: How about going to the movies?
Going out is the topic. Now that the topic has been established, it's okay to say How about to establish the subject or sub-topic, going to the movies.
It always drives me nuts when Koreans ask me out of the clear blue, how about ---? I'm like, what about ---, what the hell are you talking about? Actually I don't say that, but if I found the authors of the textbook, I would sure say it to them.
Does this sound correct? I didn't do my homework, but as usual just teaching what sounds natural to me.
What about it?
Yes, I too am bewildered by out-of-the-blue questions like "How about lunch?" meaning "What did you think of lunch?" which should really mean "Would you like to go to lunch?" Sometimes it is used on a more specific topic, like "How about David?" I want to say, "What about David?" but I have started using the question myself when talking to teachers.
Konglish
I guess if we stay in Korea long enough, all this Konglish will work its way into our daily speech. I've caught myself saying things like how's your condition? or at the time of attending elementary school....
"How about..."
How about a drink tonight? How about a cup of coffee? How about that? I think an antecedent situation is required. I go along with stron's remarks. How about cutting the crap? It all appears to me that there must be a prior understanding of something going on. How about it? How's your condition would most probably be something that your doctor or coach would ask, or at least someone aware of your previous condition. How about it?
"You look serious..."
The textbook has all sorts of odd phrases here and there. On Lesson 2 of the Grade 1 textbook (the one by Carl Dustheimer), one of the phrases is "You look serious. What's wrong?" It's been so ingrained in my students' minds that they use it EVERY day for just about EVERY thing.