I like to give my students different "writing tools". One of these tools is Rainbow Adjectives. When students write, I encourage them to paint a picture with their words. It is always better to be more descriptive when using color words. Rather than say "She dove into the clear blue ocean", I would prefer "She dove into the sparkling turquoise and cerulean waters of the ocean".
This activity shows you how to teach Rainbow words using paint chips (a free resource for you available at your local home improvement store).
This also provides a worksheet for your students to use to guide them through this activity!