As your kid's pencil skills are improving, the day is not far when you will ask your kid to draw a straight line using a pencil or crayon and she will be able to do it just the way you want it.
What you need to know:
You must assist her, you can draw coordinates at a small distance and ask your kid to join them with a small straight line. Once your kid is comfortable with this, the process of drawing straight small lines using a pencil without coordinates will be easier. This will be a great practice to improve her pencil skills.