Unit Plan 6 (Grade 1 Science): Light Sources & Shadows

Focus: Explore how light direction affects shadows and visibility, and make observations to construct an evidence-based account that objects can be seen only when illuminated by a light source.

Grade Level: 1

Subject Area: Science (Physical Science • Light • Investigation Skills)

Total Unit Duration: 5 sessions (one week), 30–45 minutes per session

I. Introduction

In this unit, students deepen their understanding that we can only see objects when there is light. They investigate different light sources (sunlight, lamps, flashlights) and explore how changing the direction of light changes what they see—especially shadows. Students test how shadows move, stretch, shrink, and change shape when a flashlight moves around an object.

Across the week, students practice making careful observations, recording results, and using those results as evidence. The unit ends with a “Light Sources & Shadows Report” where students explain how light direction affects shadows and why objects are visible only when illuminated.

Essential Questions

• What is a light source, and how does it help us see?
• How does the direction of light change a shadow?
• What patterns do we notice when we move a light closer, farther, or to the side?
• How can we use observations as evidence to explain our ideas?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Identify and describe light sources and explain that light helps us see objects (1-PS4-2).
2. Make observations that objects can be seen only when illuminated (1-PS4-2).
3. Investigate how changing light direction changes a shadow’s position, size, and shape.
4. Record results in simple tables/drawings across repeated trials and describe patterns.
5. Construct an evidence-based account (drawing + sentence) explaining how light direction affects shadows and why illumination is needed for seeing.

Standards Alignment — Grade 1 (NGSS-Aligned)

• 1-PS4-2 — Make observations to construct an evidence-based account that objects can be seen only when illuminated.
  • Example: Compare what is visible when a flashlight shines on an object from different directions and use observations of shadows as evidence that light is being blocked.

Success Criteria — Student Language

• I can name a light source (like the sun or a flashlight).
• I can explain that I can see objects only when they are illuminated.
• I can show that moving the light changes the shadow.
• I can record what I observe with pictures, labels, and simple words.
• I can use my observations as evidence to explain my idea.