Summer days provide a perfect context for sketching and experimenting with artistic styles and media. Removed from the structure of daily school life, children often enjoy their freedom to explore wonders of creation and investigate their properties through art. If you haven't done so, consider gathering some pencils, pens, paints or anything else of interest and take a jaunt outdoors for some impromptu art.
I favor realistic art, particularly highly-detailed botanical paintings, for many reasons. In studying a simple flower or plant, we develop our perception and ability to recognize how lines and shape work together to create form. By trying to copy an everyday object, we slow ourselves down and come to appreciate the finite details which make up God's grand universe.