I am teaching two classes of grade school art in our home school co-op again this year. I have about 14 students in my 3rd grade class, and about 14 in my 4/5/6th grade class.
My older class did a project where we looked "close up" using color crayons. We used a crayon as the subject and as the medium. They were to draw a portion of their crayon of choice on a sheet of paper in a close up and graphic view. Outlining in black and coloring in the details gives a nice composition. Some had time to make two versions, and enjoyed putting different halves together when done.
My younger class did a fall watercolor and resist project. They were to draw leaves in warm colors on a page and paint over them in cool colors of watercolor. We learned a bit about mixing watercolors with water to make them transparent.