Grade 4 · lesson 1 of 4

Apply a Supplied Light Model

A simple shading model places the brighter region toward the named light source and the darker region opposite it.

About 20 minutes, plus any extended practice

Supplied materials

Paper and a pencil for a sphere diagram and light-source arrow. You can label bright and dark areas.
Read this example: For an original sphere drawing, the simplified light model puts the brightest region toward the left source and deepest shade opposite it. Which value plan matches? Supplied candidates: (A) Bright toward left; dark toward right (B) Dark toward left; bright toward right (C) Every region equally dark (D) Only outline the sphere and remove all value regions.
Try this question: For an original sphere drawing, the simplified light model puts the brightest region toward the right source and deepest shade opposite it. Which value plan matches? Supplied candidates: (A) Bright toward right; dark toward left (B) Dark toward right; bright toward left (C) Every region equally dark (D) Only outline the sphere and remove all value regions.

Learn the idea

In this simple shading model, place the bright area toward the named light source and the dark area on the opposite side. These values can help a flat drawing suggest a rounded form.

Reason through the supplied case: The stated model assigns light-facing value to the left and opposing shade toward right. This contrast can suggest form on flat paper. It is a simplified drawing model, not a complete physical account of reflected or ambient light.

Real lighting also involves reflected and ambient light. This exercise checks the stipulated simplified plan, and no lamps, photography or physical sphere experiment is required.

Read the sphere-drawing rule. Find the light source and the side that should be brightest.
Explain why a source on the left puts the bright area on the left and the dark area on the right in this model.
Try the question and all three practice questions before checking their answers.
Draw a sphere diagram with a source arrow from the left and label its brighter and darker regions.
Check your work: The bright region faces the arrow’s source and the darker region lies opposite under the stated model.

Worked example

See the method in action

For an original sphere drawing, the simplified light model puts the brightest region toward the left source and deepest shade opposite it. Which value plan matches? Supplied candidates: (A) Bright toward left; dark toward right (B) Dark toward left; bright toward right (C) Every region equally dark (D) Only outline the sphere and remove all value regions. Model decision: Bright toward left; dark toward right. The stated model assigns light-facing value to the left and opposing shade toward right. This contrast can suggest form on flat paper. It is a simplified drawing model, not a complete physical account of reflected or ambient light.

Your turn

Check your reasoning

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Helpful tips

A simple shading model places the brighter region toward the named light source and the darker region opposite it.
Real lighting also involves reflected and ambient light.

See the answer and explanation

Bright toward right; dark toward left

The stated model assigns light-facing value to the right and opposing shade toward left. This contrast can suggest form on flat paper. It is a simplified drawing model, not a complete physical account of reflected or ambient light.

Take it further

Try one more question: For an original sphere drawing, the simplified light model puts the brightest region toward the lower-right source and deepest shade opposite it. Which value plan matches? Supplied candidates: (A) Bright toward lower-right; dark toward upper-left (B) Dark toward lower-right; bright toward upper-left (C) Every region equally dark (D) Only outline the sphere and remove all value regions. Answer: Bright toward lower-right; dark toward upper-left. The stated model assigns light-facing value to the lower-right and opposing shade toward upper-left. This contrast can suggest form on flat paper. It is a simplified drawing model, not a complete physical account of reflected or ambient light. Now make your own work: Draw a sphere diagram with a source arrow from the left and label its brighter and darker regions. Check your work: The bright region faces the arrow’s source and the darker region lies opposite under the stated model.

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More practice: try new cases

Choose an answer for each problem. Explain your method on paper, then use the feedback to decide what to revisit.

1. For an original sphere drawing, the simplified light model puts the brightest region toward a light source above the sphere and the deepest shade on the opposite side. Which value plan matches?Dark toward above; bright toward belowBright toward above; dark toward belowEvery region equally darkOnly outline the sphere and remove all value regions

Need a hint?

A simple shading model places the brighter region toward the named light source and the darker region opposite it.
Real lighting also involves reflected and ambient light.

2. For an original sphere drawing, the simplified light model puts the brightest region toward a light source below the sphere and the deepest shade on the opposite side. Which value plan matches?Dark toward below; bright toward aboveEvery region equally darkBright toward below; dark toward aboveOnly outline the sphere and remove all value regions

Need a hint?

A simple shading model places the brighter region toward the named light source and the darker region opposite it.
Real lighting also involves reflected and ambient light.

3. For an original sphere drawing, the simplified light model puts the brightest region toward the upper-left source and deepest shade opposite it. Which value plan matches?Dark toward upper-left; bright toward lower-rightEvery region equally darkOnly outline the sphere and remove all value regionsBright toward upper-left; dark toward lower-right

Need a hint?

A simple shading model places the brighter region toward the named light source and the darker region opposite it.
Real lighting also involves reflected and ambient light.

Your choices are temporary. Feedback appears after you check all the answers.

Nothing here is saved to an account or sent to a teacher. Keep your own notes or download them before leaving. The score describes these questions; it does not certify subject mastery.

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