Materials & Prep
Prepare drawing paper, 2B and 6B graphite pencils, kneaded erasers, regular erasers, and scrap paper for testing values. Draw or project one circle and one sphere reference with the light coming from the upper left. Have students use their existing sketchbooks or drawing paper. Confirm local procedures for safe pencil and blending-tool use if blending stumps are provided.
Opening: Predict the Missing Information
Display two drawings: a circle filled evenly with medium graphite and a sphere shaded with a light source from the upper left. Ask: “Why does one read as a flat disk while the other reads as a round object, even though both have an outline?”
Have students silently choose one explanation: the outline, the darkest value, or the placement and change of values. Students write one sentence explaining their choice, then compare with a partner. Prompt students to recall what value means in drawing and to identify where the lightest and darkest areas appear in the sphere.
ConfrontState the class’s common approach directly: an outline plus one flat fill cannot show turning form. Tell students they will test whether a value scale and a controlled light source solve that problem.
Demonstration: Build Values and Model the Sphere
DisplayLabel the light source with an arrow pointing from the upper left. Explain that every value on the sphere must make sense in relation to that one light source.
Worked example
Create a seven-step graphite scale from left to right
- White paper
- Very light graphite
- Light gray
- Middle gray
- Dark gray
- Very dark gray
- Near black
Think aloudI first make seven separate boxes, rather than shading one continuous strip. I press lightly for Step 2, increase pressure gradually through Steps 3 and 4, and use repeated layers instead of pressing hard immediately. I test each box beside the next one. The common mistake is making Steps 3, 4, and 5 nearly identical. If I cannot tell them apart, I lighten Step 3 or darken Step 5 before using the scale.
ModelOn the circle, lightly place the highlight near the upper left. Shade the broad middle area with Value 4, gradually darken toward the lower right through Values 5 and 6, and place the core shadow near the lower-right edge with Value 6 or 7. Leave a narrow band of Value 3 near the lower edge as reflected light. Add a cast shadow on the ground extending down and right, darkest near the sphere and softer farther away.
ExplainReflected light is not a second light source. It is a small, lighter area at the shadow edge that still remains darker than the light side. The cast shadow must point away from the light source, so an upper-left light produces a shadow toward the lower right.
Check for understandingStudents point to or name the highlight, core shadow, reflected light, and cast shadow on the model. Ask, “If the light stays upper left, where must the cast shadow go?” Require the answer “lower right” and ask one student to justify it.
Guided Practice: Test Values and Plan the Sphere
Have students create the seven-step scale beside their drawing area. They compare each box to the projected scale and adjust at least one value that is too similar to its neighbor.
ScaffoldProvide a four-zone guide on the board: light side, turning middle, core shadow, and reflected-light edge. Students lightly draw these zones inside a circle before shading. Use the sentence frame, “Because the light comes from , the darkest part should be and the cast shadow should extend .”
ModelShade the first half of the sphere with students. Students place Value 2 at the highlight, Values 3 and 4 across the turning form, and Value 5 in the beginning of the shadow side. Pause before the core shadow and ask students to hold up fingers 1 through 7 to show the value they plan to use.
CirculateLook first for flat filling, an outline that is darker than the form, or a cast shadow that points toward the light. Ask, “What does your light-source arrow require this area to do?” Have students revise with layered pencil strokes rather than smearing the entire form.
Independent Studio: Shade the Sphere
Students complete one graphite sphere using their value scale and the upper-left light source. They must show a highlight, gradual transition, core shadow, reflected light, and cast shadow. They may use a kneaded eraser to lift the highlight after shading, but the value changes should come mainly from controlled graphite layers.
ExtensionStudents who finish early create a second sphere with the light source moved to the upper right. They must keep the same seven-value scale and explain how the highlight, core shadow, reflected light, and cast shadow moved.
ConfrontIf a student has outlined and filled the sphere flat, have the student place a sticky note or pencil mark at the light-source arrow, identify the light side and shadow side, then revise only one zone at a time. Do not erase the whole drawing before identifying the value problem.
Closing Check: Evidence of Form
Students place the value scale beside the finished sphere and complete an exit ticket: “The light comes from . My highlight is at . My core shadow is at . My reflected light is at . My cast shadow extends because .”
Students circle one area where the value changes gradually and put a small X beside the area that most needs revision. Collect the drawing and exit ticket together. A successful response includes a readable value scale, a consistent upper-left light source, and all five visible form cues: highlight, transition, core shadow, reflected light, and cast shadow.