Paint by numbers

Paint is any pigmented liquid, liquefiable, or solid mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture. Paint can be made or purchased in many colors—and in many different types. Paint is typically stored, sold, and applied as a liquid, but most types dry into a solid. Most paints are either oil-based or water-based and each has distinct characteristics. For one, it is illegal in most municipalities to discard oil-based paint down household drains or sewers. Clean-up solvents are also different for water-based paint than they are for oil-based paint. Water-based paints and oil-based paints will cure differently based on the outside ambient temperature of the object being painted (such as a house.) Usually, the object being painted must be over 10 °C (50 °F), although some manufacturers of external paints/primers claim they can be applied when temperatures are as low as 2 °C (35 °F).

Paint by numbers is a system where a picture is divided into shapes, each marked with a number that corresponds to a particular color. You paint in each shape and ultimately the picture emerges as a finished painting. The paint by numbers approach is often ridiculed as being simplistic, uncreative, and formulaic. I believe it's helpful in getting across the concept that a painting is built up through multiple shapes of color. These shapes often don't make sense individually, nor look like anything "real", but put together as a group they create the image.