If you're truly interested in knowing the answers to your questions, DRAW. Really draw, decide what to draw and try to draw it, then do it again and again and again.
Why would your children like it when you don't.
I'm glad to hear that schools are having kids draw because it's so enriching. When drawing the brain has to think in a different way. There has to be fore thought, one has to think of movement and gesture. Thought and mood has to be caught in the drawing, in color. It must express meaning and speak of a mood or idea. It can tell you whether the child understands the lesson. It can tell you much about the child's thoughts and emotional state. A person that draws well or likes to draw, practices drawing learns to observe carefully. They take in the environment with a sense of space and color and livingness. This can only lead to intelligence. Drawing/painting and the like can help a person in many ways and it certainly brings on a fuller and more enriching interior life, for what ever you draw or paint you study. You study its curves, its lines, its tones and hues, the way it moves the way it grows, and on and on. You become a part of it in a way by feeling and thinking about what you're drawing.
All Subjects overlap and combine with each other to some degree or another. Everything is inter-dependent, there is nothing not connected to something else. Even in Math one is using language.
Education is a whole picture for whole children. People are not just a brain in a body or a body with a brain.
I feel for ya for not being able to give your child an answer. But consider that she is speaking what she senses from you first and foremost. If she doesn't like to draw because she's unhappy with the results it only makes it harder when she knows it is not valued by you, her mother. You could tell her that drawing does help her spelling because she is now using color and gesture to show words. How would it look if we couldn't use the letters in words and only used drawing how we show it?" You could also say something like, "Isn't it nice to have some time to draw now instead of only writing out words."
Drawing, painting, modeling, sculpting has always been used in a proper education as part of the whole education. It produced a real Knowing of subjects. Any good scientist or teacher and many others that keep records or research journals always draws their findings along with their written work.
In many prep schools, charter schools, private schools have students draw throughout school. Waldorf education has drawing as part their education from beginning to end. Again this opens up pathways in the brain that other wise would have little exercise and therefore thinking is expanded, problem solving is exercise, because drawing is one big exercise is problem solving.
This is just the gist of it even though I've written much.
Help yourself and children by embracing drawing and maybe painting too. Let them experience a mom that can change, grow, expand and experiment. Just Draw.