Start with the basics. Allow younger children to experiment with color. Explain how the three primary colors--red, blue and yellow--can blend together to create secondary colors. Give each child a small amount of the primary acrylic paints and allow them to mix them in a shallow container with a mixing knife. Use a color wheel to show where the colors are located and what they look like.
Experiment with line. Use a set of pencils ranging in hardness from #4B to #4H to explore how soft and hard pencils make different marks on a sheet of paper. Let students experiment with the pencils to draw vertical, horizontal and curvy lines.
Assess a piece of art. Show younger children a simple composition and talk about the basics. Describe what a shadow is and how it falls on an object. Discuss the color and line of a piece, whether primary or secondary colors are used and what kinds of lines were incorporated to make the piece. Ask children to point out specific aspects of the artwork to help them recognize basic art principles.
Let students create their own artwork. Construct a lesson incorporating the line techniques and color theory recently covered and ask the young students to create their own artwork. Decide on a topic or theme to illustrate and then discuss the elements of the composition each child has created.
Delve into color theory. Talk about the relationships between primary, secondary and tertiary colors. Give your older students primary and secondary colored paints and ask them to mix tertiary colors of yellow-orange, red-orange, red-violet, blue-violet, blue-green and yellow-green with a mixing knife. Have students paint a small square of each color in the color wheel on bristol board.
Discuss value. Talk about tints, shades and tones of color. A tint is a color mixed with white, a tone is a color mixed with gray and a shade is a color mixed with black. Compare and contrast value in a basic composition and discuss how the value conveys different emotions or moods of a piece of art.
Start sketching. Give an older student a set of pencils and a sketchbook. Set up simple still-life compositions containing basic geometric objects such as a ball, a box and a cone. Let students practice making simple contour drawings to outline the shape of each object.
Learn about shading. After mastering the basics of drawing objects with simple line drawings, explore value again, but this time work on shading. Show students a simple drawing and describe how the light effects the value of the shadow that falls on and around an object. Help students begin to shade their compositions by filling in areas of their drawing with light and dark shadows.
Color the composition. Once finished with their sketch, help them color the objects they've drawn using the same principles they have learned about color. With colored pencils, fill in the composition. Talk about choosing a color scheme; monochromatic colors are variations on a single color, complementary are colors that are opposite on the color wheel. An analogous color scheme uses a primary color and two adjacent colors on the color wheel. Talk about how each color scheme effects the mood of the composition.