Excerpt from a raisin in the sun: act i, scene i

ruth sit down and have your breakfast, travis.
travis mama, this is friday. (gleefully) check coming tomorrow, huh?
ruth you get your mind off money and eat your breakfast.
travis (eating) this is the morning we supposed to bring the fifty cents to school.
ruth well, i ain't got no fifty cents this morning. travis teacher say we have to.
ruth i don't care what teacher say. i ain't got it. eat your breakfast, travis.
travis i am eating.
ruth hush up now and just eat!
(the boy gives her an exasperated look for her lack of understanding, and eats grudgingly)
travis you think grandmama would have it?
ruth no! and i want you to stop asking your grandmother for money, you hear me?
travis (outraged) gaaaleee! i don't ask her, she just gimme it sometimes!
ruth travis willard younger i got too much on me this morning to be …
travis maybe daddy
ruth travis!
(the boy hushes abruptly. they are both quiet and tense for several seconds)
travis (presently) could i maybe go carry some groceries in front of the supermarket for a little while after school then?

ruth just hush, i said. (travis jabs his spoon into his cereal bowl viciously, and rests his head in anger upon his fists) if you through eating, you can get over there and make up your bed.

(the boy obeys stiffly and crosses the room, almost mechanically, to the bed and more or less folds the bedding into a heap, then angrily gets his books and cap)

travis (sulking and standing apart from her unnaturally) i'm gone.
ruth (looking up from the stove to inspect him automatically) come here. (he crosses to her and she studies his head) if you don't take this comb and fix this here head, you better! (travis puts down his books with a great sigh of oppression, and crosses to the mirror. his mother mutters under her breath about his "slubbornness") 'bout to march out of here with that head looking just like chickens slept in it! i just don't know where you get your slubborn ways . , and get your jacket, too. looks chilly out this morning.

travis (with conspicuously brushed hair and jacket) i’m gone.
ruth get carfare and milk money (waving one finger) and not a single penny for no caps, you hear me?
travis (with sullen politeness) yes'm.

question: in this excerpt from a raisin in the sun, what effect do stage directions have on your understanding of the scene? explain your answer and support it with evidence from the text.