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Living Clocks

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Living Clocks

In this activity about daily rhythms (on page 17 of the PDF), learners will explore circadian patterns in humans, animals and plants. They will observe that some behaviors and functions of living organisms vary predictably every 24 hours and many regular functions are governed by internal "clocks," which run independently but are cued or reset by the environment. Groups of learners can conduct one of four (or more) body clock investigations: body temperature, animal behavior, bean leaf, and alertness/heart rate. Materials required for each group will vary, depending on the investigation(s) being conducted. This lesson guide includes background information, setup and management tips, extensions and a handout.

Quick Guide

Preparation Time:
Under 5 minutes

Learning Time:
1 to 7 days

Estimated Materials Cost:
$1 - $5 per group of students

Age Range:
Ages 8 - 14

Resource Types:
Activity, Experiment/Lab Activity, Lesson/Lesson Plan


Materials List (per group of students)

  • Digital thermometer with several sterile covers (and access to a fever thermometer at home)
  • Copy of student sheet (p. 20)
  • Source of natural sunlight, or fluorescent "grow light" with timer
  • 4 bean plants (purchase or grow in small pots from seed)
  • Study animals that can be observed in the classroom throughout the day (gerbils, birds, crickets, etc.)
  • Science journals or graph paper
  • Stopwatch or timer (if necessary)
  • Other materials as needed


  • Earth and Space Science
    • Earth, Moon and Sun
      • Days
  • Life Sciences
    • Diversity of Life
      • Plants
      • Animals
    • Ecology
    • Heredity and Genetics
      • Human Genetics
    • Human Body
      • The Brain and Nervous System
      • Circulation
      • Health and Nutrition
  • Mathematics
    • Algebra
      • Patterns
    • Data Analysis and Probability
      • Data Analysis
      • Data Collection
      • Data Representation
    • Measurement
      • Rate
    • Problem Solving
    • Reasoning and Proof
    • Representation
  • Physical Sciences
    • Heat and Thermodynamics
      • Heat and Temperature
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations
      • Gathering Data
      • Formulating Explanations
      • Communicating Results

Informal Categories

  • Animals
  • Gardening
  • Nature and Environment


To use this activity, learners need to:

  • see
  • read
  • touch

Learning styles supported:

  • Involves teamwork and communication skills
  • Involves hands-on or lab activities


Includes alignment to state and/or national standards

This resource is part of:

Access Rights:

  • Free access


  • Moreno, Nancy P.; Tharp, Barbara Z.; Vogt, Greg L.


  • All Rights Reserved, Baylor College of Medicine, ©2009

Funding Source:

  • NASA, NCC 9-58