Changing Shadow Patterns

Overview

This 62-minute lesson engages 5th grade students in exploring how shadows change in length and direction throughout the day. Students will develop and use models to explain these changes based on the position of the Sun relative to objects on Earth. The lesson builds towards meeting the Next Generation Science Standards (NGSS) standard 5-PS2-1 through hands-on investigation, collaboration, and scientific modeling.

---

NGSS Alignment

Performance Expectation:

• 5-PS2-1: Support an argument that the gravitational force exerted by Earth on objects is directed down.

Disciplinary Core Idea (DCI):

• PS2.B: The gravitational force of Earth acting on an object at Earth's surface pulls that object toward the planet’s center.

Science and Engineering Practice (SEP):

• Develop and use models to describe phenomena.

Crosscutting Concept (CCC):

• Patterns: Observed patterns in nature guide explanations.

---

Learning Objectives

By the end of this lesson, students will be able to:

1. Observe and record changes in the length and direction of shadows at different times of the day.
2. Develop a model showing how the Sun’s position affects shadow length and direction.
3. Use their model to explain observed patterns in shadow changes.
4. Communicate their understanding using proper scientific vocabulary (e.g., Sun’s position, shadow, length, direction, model).

---

Materials Needed

• Flashlights (1 per group) or access to outdoor sunlight
• Small objects for casting shadows (blocks, figurines, pencils)
• Protractors (to measure shadow angles)
• Tape measures or rulers
• Clipboards and recording sheets
• Whiteboard and markers
• Chart paper or large drawing paper for group models

---

Lesson Schedule

1. Introduction (10 minutes)

• Engage: Show 2 images or pictures of the same object casting very different shadows (e.g., a tree in the morning vs. mid-afternoon). Ask: Why do you think the shadows look so different?
• Background: Briefly explain that shadows change because of the Sun’s position in the sky as the Earth turns.
• Connect to Standards: Tell students today they’ll create and use models to explain how and why these shadow changes happen.

---

2. Investigation Setup (5 minutes)

• Arrange students into small groups (4-5 students each).
• Explain that each group will use a flashlight (or go outside if feasible) to observe shadows at different “times of day” by changing the flashlight’s angle.
• Demonstrate how shadows change with flashlight position by holding up an object and moving the light source slowly from low to high angles.

---

3. Data Collection & Observation (15 minutes)

• Groups take turns shining the flashlight at different angles representing morning (low angle), noon (highest angle), and afternoon (medium angle).
• Students measure and record the length of the shadow and the direction (angle) relative to the object’s base using rulers and protractors.
• Record observations on worksheets: time label, shadow length, shadow direction (angle), and a quick sketch of the shadow.

---

4. Modeling Activity (15 minutes)

• Develop Models: On large chart paper, each group creates a diagram showing:
  a) The position of the Sun (flashlight) relative to the object at three times (morning, noon, afternoon)
  b) Corresponding shadow lengths and directions
• Encourage inclusion of arrows to illustrate Sun direction and shadow orientation.
• Prompt students to think about how changing the Sun’s height affects shadow length and how the Sun’s position affects shadow direction.
• Teacher circulates to support groups, asking probing questions like: What happens to the shadow length when the Sun is higher? Why does the shadow change direction?

---

5. Group Presentations & Discussion (10 minutes)

• Each group presents their model and explains how it shows the shadow changes throughout the day.
• Facilitate class discussion with questions:
  • What patterns did you notice about shadow length?
  • How does the Sun’s height affect the shadow?
  • Why does the shadow move around the object?
• Highlight key scientific vocabulary and how the model explains the phenomenon.

---

6. Wrap-Up & Assessment (7 minutes)

• Exit Ticket: Each student writes a brief response to the question:
  Explain how and why the length and direction of a shadow change throughout the day.
• Collect responses to assess individual understanding aligned with NGSS practices.
• Recap the main idea: Shadows change because Earth rotates, changing the Sun’s position relative to objects.

---

Differentiation & Extensions

• For advanced learners: Challenge them to create 3D physical models with sticks and paper to demonstrate shadow changes more realistically.
• For English Language Learners or students needing support: Provide sentence frames for writing exit tickets and vocabulary flashcards with images illustrating key terms.
• Extension: Encourage students to observe and record real shadows at home at morning, noon, and afternoon, then compare to class models the following day.

---

Teacher Reflection Prompts

• Did students accurately measure and describe shadow length and direction?
• Were models detailed and scientifically accurate?
• How well did students use scientific vocabulary in explanations?
• What modifications could increase engagement or deepen understanding next time?

---

This lesson actively involves students in developing and using models—a key NGSS science and engineering practice—to explain observable natural patterns, exactly matching the intent of 5th grade standards. The multi-modal approach ensures concepts are accessible and memorable, setting a strong foundation for future Earth and space science learning.