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What Makes Life, Life?

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Krista Larsen

Tier 1
For Schools

Lesson Plan

Characteristics Lesson Plan

Students will identify the seven characteristics of life, explain each standard, and apply them to classify real-world examples in small groups.

Understanding what defines life lays the foundation for all biology topics; this lesson helps students distinguish living vs. nonliving systems and builds critical thinking skills.

Audience

9th Grade

Time

30 minutes

Approach

Interactive slides, group classification activity, and quick quiz

Materials

  • Projector, - Whiteboard and Markers, - Characteristics of Life Overview Slides, - Characteristics of Life Activity Worksheet, and - Characteristics of Life Exit Ticket Quiz

Prep

Review and Prepare Materials

10 minutes

  • Review Characteristics of Life Overview Slides
  • Print copies of Characteristics of Life Activity Worksheet for each student
  • Print the Characteristics of Life Exit Ticket Quiz
  • Arrange desks for small-group discussions
  • Test the projector and queue the slides

Step 1

Warm-Up Discussion

5 minutes

  • Ask students: “What does it mean to be alive?”
  • List student responses on the whiteboard
  • Introduce the idea of characteristics/standards as criteria for life

Step 2

Direct Instruction

10 minutes

  • Display Characteristics of Life Overview Slides
  • Define each characteristic: organization, metabolism, homeostasis, growth, reproduction, response to stimuli, adaptation
  • Provide one real-world example per characteristic
  • Check for understanding with quick thumbs-up/thumbs-down prompts

Step 3

Group Activity

8 minutes

  • Divide students into small groups (3–4 each)
  • Distribute Characteristics of Life Activity Worksheet
  • Instruct groups to classify given scenarios as living or nonliving and list which characteristics apply
  • Circulate to support and ask probing questions

Step 4

Exit Ticket Quiz

5 minutes

  • Hand out Characteristics of Life Exit Ticket Quiz
  • Students complete quiz individually, identifying characteristics in new examples
  • Collect quizzes for formative assessment

Step 5

Cool-Down Reflection

2 minutes

  • Ask students to share one new fact they learned today
  • Prompt: “Give an example of something you once thought was alive but now know isn’t, and explain why.”
  • Highlight how the standards help clarify definitions of life
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Slide Deck

What Makes Life, Life?

An exploration of the seven characteristics that define living organisms.

Welcome students! Introduce today’s essential question: “What makes something alive?” Explain that we will explore the seven characteristics scientists use to define life.

Learning Objectives

• Identify and define the seven characteristics of life
• Provide real-world examples for each characteristic
• Reflect on why these criteria matter in biology

Read through each objective so students know what to expect. Encourage them to listen for examples.

Characteristic 1: Organization

All living things exhibit a complex but ordered structure:
• Cells → Tissues → Organs → Systems → Organism

Explain that every living organism is organized into levels – from cells up to organ systems. Show a diagram or quick sketch if possible.

Characteristic 2: Metabolism

Living organisms take in energy and materials to power life processes:
• Anabolism: building complex molecules
• Catabolism: breaking down molecules for energy

Define metabolism and highlight both the building up (anabolism) and breaking down (catabolism) of materials. Ask for daily-life examples.

Characteristic 3: Homeostasis

The ability to maintain a constant internal environment despite external changes, e.g.:
• Thermoregulation
• pH balance
• Water balance

Discuss homeostasis as maintaining stable internal conditions. Use body temperature or blood sugar as examples.

Characteristic 4: Growth and Development

Living things grow (cell division and enlargement) and follow a developmental plan:
• Embryo → Juvenile → Adult stages

Clarify that growth is an increase in size/number of cells, while development refers to changes over a lifetime. Use a seed-to-plant example.

Characteristic 5: Reproduction

The process by which organisms produce new individuals of the same species:
• Sexual reproduction (genetic diversity)
• Asexual reproduction (clones)

Explain reproduction’s two forms—sexual and asexual. Ask why reproduction is essential for species survival.

Characteristic 6: Response to Stimuli

Organisms detect and respond to environmental changes:
• Light, temperature, chemicals, pressure
• Reflexes and behaviors

Give examples like plants bending toward light or our pupils constricting. Emphasize quick and slow responses.

Characteristic 7: Adaptation

Heritable traits that enhance survival and reproduction in a particular environment, developed over many generations.

Talk about adaptation over many generations. Reference Darwin’s finches or antibiotic resistance in bacteria.

Review & Discussion

  1. Organization 2. Metabolism 3. Homeostasis 4. Growth & Development 5. Reproduction 6. Response to Stimuli 7. Adaptation

Discussion Prompt:
Would you categorize a virus as living? Explain your reasoning.

Quickly recap all seven characteristics. Then prompt students to discuss in pairs or small groups: “Would you consider a virus alive? Why or why not based on these criteria?”

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Worksheet

Characteristics of Life Activity Worksheet

Instructions: Using your knowledge from the lesson and the Characteristics of Life Overview Slides, classify each scenario as Living or Nonliving, then list which of the seven characteristics of life are present and which are absent. Finally, explain your reasoning in complete sentences.

Scenario 1: A sprouting seed in a garden

  1. Classification (Living or Nonliving?):



  1. Characteristics Present (choose from Organization, Metabolism, Homeostasis, Growth & Development, Reproduction, Response to Stimuli, Adaptation):






  1. Characteristics Absent:






  1. Explanation:











Scenario 2: A burning campfire at a campsite

  1. Classification (Living or Nonliving?):



  1. Characteristics Present:






  1. Characteristics Absent:






  1. Explanation:











Scenario 3: A virus infecting a cell

  1. Classification (Living or Nonliving?):



  1. Characteristics Present:






  1. Characteristics Absent:






  1. Explanation:











Scenario 4: A smartphone running apps and receiving messages

  1. Classification (Living or Nonliving?):



  1. Characteristics Present:






  1. Characteristics Absent:






  1. Explanation:











Once your group has completed all four scenarios, be prepared to share one example where classification wasn’t straightforward and explain how the characteristics of life helped you decide.

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Quiz

Characteristics of Life Exit Ticket Quiz

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Cool Down

Characteristics of Life Cool-Down

Take 2 minutes to reflect and answer the questions below. Be prepared to share responses as we wrap up.

  1. What is one new fact you learned today about the characteristics of life?



  1. Give an example of something you once thought was alive but now know isn’t.
    • Identify at least two characteristics of life that it does not meet.






  1. Rate your confidence in identifying and explaining the seven characteristics of life (circle one):
    1 2 3 4 5
    (1 = Not confident at all; 5 = Very confident)



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