What does the poet mean by 'And watching Sissy play'?

Directions: Read the following poem to answer the given question.

FRONTIER LIFE
My stockings have a hole in them,
I'm learning how to darn.
Which means that I am mending them
With needle and some yarn.

Ma says my dress is getting short,
We must let out the hem.
My only shoes have come apart,
And Pa is patching them.

The garden must be weeded,
If we want food to eat.
I pick those scratchy blackberries
So we'll have something sweet.

I help my Pa by milking Bess
And stake her out each day.
I help my Ma by hanging clothes
And watching Sissy play.

I go to bed so tired,
And get up before the sun.
There's always work that's waiting.
It never gets all done.
   
But Ma has made Pa promise
To have a family rule
If there's a teacher hired,
I get to go to school!

    Cindy Breedlove