alternative I can think of!" (Williams, 12).

Ironically, Amanda is describing her exact experience without acknowledging the fact that she too is a struggling single woman. It is also ironic that Amanda criticizes Laura for lacking the essential skills to attain a job and independently support herself because Amanda does not possess any prerequisite skills herself. Amanda was a "barely tolerated spinster" who had to rely on her family's support and suffered humility her entire life. However, she refuses to acknowledge that she has squandered her own opportunities to become independent and speaks about the disastrous effects of being unskilled and alone in a harsh world as if she had not personally experienced that exact situation.

There are a few other examples of irony besides the one that the first educator response excellently explains.

The strongest example of irony is when Amanda preaches to Laura about her future now that she has dropped out of business college.

Amanda describes “barely tolerated spinsters” who eat “the crust of humility all their lives.” The irony is that Amanda herself is a kind of spinster. Although she did marry, her husband deserted her years ago. Moreover, her strained relationship with both Tom and Laura indicates that she is “barely tolerated.” Amanda is referring to Laura’s dismal potential future if she has neither a career nor husband, yet Amanda is also talking about herself—whether she is willing to admit it or not.

Let us remember that irony is defined as the gap between appearance and reality and how it is exploited. There is an excellent example of situational irony at the beginning of this scene when Amanda comes back into the appartment and surprises Laura when she is polishing and cleaning her glass menagerie. Note Laura's reaction when she greets her mother:

Hello, Mother, I was-- (She makes a nervous gesture toward the chart on the wall. AMANDA leans against the shut door and stared at LAURA with a martyred look.)

What is ironic about this section of the play is that Laura pretends to be busy working at her typewriting course, when she has given that up months ago. However, Laura doesn't know that such gestures are completely unnecessary because her mother has just gone to her college where Laura is supposedly studying and found out the truth. Laura cannot pretend to be working hard on her studies any more.

There are plenty of instances of irony in Tennessee Williams's play The Glass Menagerie. Let's look at a few.

Amanda Wingfield, the mother of Tom and Laura, is a dreamer. She lives in the past and in the future rather than in the present. She is always telling stories of her days as a Southern belle and dreaming of how Laura could marry and have a good life. Yet Amanda accuses Tom of being a “selfish dreamer” who lives “in a dream world” and manufactures illusions, not taking care of his responsibilities to his family.

There is a deep irony in her words. Tom has been working in a warehouse, putting his dreams on hold to care for his mother and sister while Amanda clings to the illusion that Laura will marry a fine man, and that she herself is still the Southern belle she once was. The reality is much different. Tom knows it, and the audience knows it.

We can also find a good example of dramatic irony when the lights go out during the Wingfields' dinner with Jim O'Connor. Tom has not paid the light bill, and this comes as no surprise to the audience. We have already witnessed the conversation between Tom and Jim about how Tom used the money to enter the Union of Merchant Seaman. Amanda is quick to blame Tom for not paying the bill, but she does not know his motive. She thinks he merely stupidly forgot and blames him for his carelessness. The dramatic irony comes in the fact that the audiences know that she is wrong. If she had asked rather than scolded, she might have discovered the truth.

One of the more significant examples of dramatic irony--a contradiction between what a character thinks and what the reader or audience knows to be true--is Amanda's remark to Tom in their final dialogue:

"Go, then!  Then go to the moon--you selfish dreamer!"

Of course, the irony here is that in many respects, Amanda is both selfish and a dreamer herself.  For all her concern about Laura and Tom, at the heart of this concern is Amanda's desire to secure her future.  If, for instance, Laura marries a gentleman caller, then Amanda can be taken care of in her old age.  Likewise, if Tom continues to support the family and not abandon them as his father has, Amanda will also be safe. She is not concerned about Tom's artistic desires; she simply wants him to serve his sister and her. 

That she is a dreamer is clearly evinced in Scene 6 when Amanda attends Laura's dressing as thoug it her wedding dress that she ceremoniously alters for her daughter.  The significance that she places upon this visit from one of Tom's friends is also unrealistic.  For example, she interrogates Tom about Jim O'Connor, wanting to know his name, what he looks like, what his salary is, if he drinks, if he has character, etc.  Then, when Jim arrives, Amanda greets him in the voice of a Southern belle, sweeping Jim away with her "gay laughter and chatter." Besides, she is dressed as in her youth, shocking Tom at her appearance.  And, yet she tells Laura in at one point in the scene, 

"Fantastic whim and behavior. Preposterous goings on!"

To answer your question about Amanda being ironic:

She is an icon that represents the stranded, stagnant, and quite unconventional Old South.

Amanda was strategically given characteristics that go hand in hand with her way of mind, and mannerisms: They conform to the dynamics of the US South its paradigms.

For example: Amanda is the typical Southern belle, expecting the "Gentlemen Callers", dressing up all pompous and over-working to over-entertain for a quite casual afternoon with Jim. She also has the Southern habit of embellishing her tales, repeating old stories, and being a charmer, hence, her Southern Hospitality.

In addition to that, she expects the same for her daughter, and is oblivious to the needs of his son, all for the sake of keeping up with the preoccupations that in another time and place would have mattered when she was younger.

Amanda is also preocupied with appeareances, and the need to keep them. Even though Mr. Wingfield had left the family in the most miserable manner, she still managed to stay firm to the tradition and had his pictured displayed huge in the living room. She also takes great pride on her pedigree, making comments about the grandiosity of her days in the South, and somehow always managing to remain there, in her mind.

What is IRONIC about all this is that she is living in a different time and place, where industrialism is drowning workers everywhere, where there is an economic depression going on, where her son and daughter are lost in cluelessness, and in a place where none of her actions would be considered typical in a fast-moving, dynamic city.

Imagine how ridiculous or strange her demeanor looked in front of Jim when she was being so extremely hospitable, witty, and exceedingly charming. She was also awkwardly over-dressed, and she had pre-planned way too much for a casual meeting. Jim, being a city guy, probably thought of this as the doings of an "odd old lady" and probably felt very weird in the process as well.

I don't see much irony in Amanda. Her position in the small family is clear, and her choices are limited. Amanda is a worried mother who has long ago been abandoned by her husband and left to raise two children by herself. She is worried about her older son, Tom, because she knows that he is not happy living in their little apartment. She knows he wants nothing more than to escape. This frightens Amanda greatly because of her other child, Laura. Laura is a shy and nervous girl, the kind of person who, her mother fears, will never be able to take care of herself. Thus Amanda's whole goal is to find a man for Laura so that when Tom is gone and she is dead, at least Laura will be taken care of.

So, Amanda's entire quest is to find someone for Laura... a gentleman caller who will come, fall deeply in love with Laura, whisk her away, and live happily ever after. This dream of Amanda's is highly unrealistic and ultimately damaging and the source of great disappointment, but there's no irony in Amanda, just an abject desperation that engenders impracticable expectations.

Now, of course, as Amanda incessantly tells the story of her youth to her children, she relates a tale of wealth and privilege and boys who were all competing for her favors and attention. If all of her stories were true, there would be great irony in relation to her present situation of poverty and abandonment. But, sadly, there's no way to know if any of that was real.