She gathers the colors she wants.  Sometimes a rainbow has only one color in different shades.  Sometimes it has every color she can find.  She picks paper - usually construction paper, but junk mail envelopes and pages from her journal and blank white drawing paper are also popular choices.  Then she draws a line.  Then she scribbles little blocks of each color.  And when she is finished, she puts her name in the corner of the paper and scampers to the fridge to hang up her masterpiece.  I never want to forget what our kitchen looks like bursting at the seams with drawings of rainbows.