Hi,

Would love to brainstorm some ideas, but I'm not sure exactly what you mean.  Each of those words has multiple uses and meanings.  Could you provide an example of each in context so we can see which uses you're interested in?

Thanks,

Heath

After a quick look at 'how to' in the Oxford Guide to English Grammar (I'm gonna call it OGEG from now on), the first thing I'd suggest is that 'how' needs to be focused on separately from 'as' and 'like'. 

The OGEG groups 'how to' with other question words.  Meaning/Use:  indirect questions asking about what the best action is.  Structure/form:  question word + to + infinitive

So, I'd suggest a lesson based around example sentences like this:

• I have a big problem and I don't know what to do.
• Could you tell me how to spell that?
• We've got to hurry.  Make up your mind where to go now, or we'll stay home!

I also think you'd be best off dealing with the other's separately too.  One lesson on:

• look + like = two people are similar in appearance  (David looks like his mother.)
• be + like = two people are similar  (He's like his father.  He has that same dry sense of humour.)
• act + like = two people have similar behaviour  (Stop acting like a child!)

And another lesson on:

• "Maria has come along as our guide. (She is our guide.)"  [Taken directly from OGEG]
• "I'm having to use the sofa as my bed. (It is my bed.)"  [Taken directly from OGEG]
• He's working as a waiter.  (He is a waiter).

I'm not sure beyond that.  Let me know what you decide to do and if you get some good ideas.

Sorry, my intended suggestion got lost amidst all the language analysis.  What I really meant was:

• Focus on each one alone.

That is, I've heard that when people learn pairs of words that are similar in meaning (eg. left/right, study/learn, etc) or sound (eg. kitchen, chicken) at the same time, that there's a good chance those words get mixed up for them.  It can be useful to contrast them, but it's best if they've been introduced, focused on and practised in isolation for a while first.

Maybe the Portuguese influence is part of the reason why it's difficult for them, but it might just be an 'interlanguage' thing that affects a lot of different English learners.  Try teaching each expression alone for a while and see if that helps.

Also, I haven't looked up 'how' for comparisons (your original example was more about use than comparison) in a grammar reference book yet, but there seems to be a clear difference in meaning when it comes to 'as' and 'like'.  As = the same / is.  Like = similar (but not the same).  Compare:

• She's as tall as her father.  (=they are the same height)
• She's working as a guide.  (=she actually is a guide)
• She looks like her father.  (=there are similarities in their appearance; but she doesn't actually have a beard, a man's skin, or look the same age as him)
• She's always acting like a monkey.  (=her behaviour is similar to a monkey; but she doesn't actually swing in trees and pick insects out of her hair)

So if you do want to go for contrast, this kind of focus might help (you'd have to look up 'how' in a grammar reference book to clarify that too)... but I'd still recommend treating them completely separately, instead.