Unit Plan 10 (Grade 3 Science): Life Cycles Overview

Focus: Model birth, growth, reproduction, and death in plants and animals and compare similarities and differences in life cycles.

Grade Level: 3

Subject Area: Science (Life Science)

Total Unit Duration: 5 sessions (one week), 45–60 minutes per session

I. Introduction

In this unit, students build a big-picture understanding of life cycles. They explore how plants and animals all go through birth, growth, reproduction, and death, but with different timing, stages, and structures. Through diagrams, simple investigations, and short texts, they compare life cycles of familiar organisms (e.g., butterflies, frogs, flowering plants, humans) and use models to show both diversity and patterns. Students end the week by creating their own Life Cycle Model that clearly communicates each major stage.

Essential Questions

• What stages do all living things go through during their life cycles?
• How are the life cycles of different organisms similar and different?
• Why is reproduction an important part of every life cycle?
• How can models (diagrams, wheels, flipbooks) help us understand and explain life cycles?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Identify and describe key life cycle stages (birth, growth, reproduction, death) for multiple organisms.
2. Create life cycle models (diagrams, wheels, or flipbooks) to show the sequence of stages for plants and animals.
3. Compare and contrast life cycles of at least two organisms, noting both shared patterns and differences.
4. Use simple texts, pictures, and observations as evidence for how an organism changes over time.
5. Explain in their own words why reproduction is a necessary part of a life cycle for a species to continue.

Standards Alignment — 3rd Grade (NGSS-Aligned)

• 3-LS1-1 — Develop models to describe that organisms have unique and diverse life cycles, but all have birth, growth, reproduction, and death.
  • Example: Draw and label life cycle diagrams for a butterfly and a plant, then highlight the stages that match (e.g., birth → growth → reproduction → death).

Success Criteria — Student Language

• I can name and describe the main stages in an organism’s life cycle.
• I can draw or build a model that shows life cycle stages in the correct order.
• I can compare two life cycles and tell how they are alike and different.
• I can use pictures, diagrams, or short readings to support my ideas about how an organism changes over time.
• I can explain why reproduction is important for a group of organisms to keep existing.