Survival of the Fittest: Variations in the Clam Species Clamys sweetus

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This guided inquiry three-part activity engages learners in thinking about the mechanism of natural selection by encouraging them to formulate questions that can be answered through scientific investigation, data collection and pattern recognition. Learners are given a scenario in which a new species of clam is discovered. They will use M&Ms and Reese's Pieces and other simple materials to study variations within the clam population. Learners will collect and plot data to draw conclusions.

Quick Guide

Preparation Time:
10 to 30 minutes

Learning Time:
2 to 4 hours

Estimated Materials Cost:
$10 - $20 per group of students

Age Range:
Ages 11 - 18

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


Materials List (per group of students)

  • 12 sealable storage bags marked “C. sweetus strain M” (10 M&M candies minus the brown ones)
  • 12 sealable storage bags marked “C. sweetus strain R” (10 Reese’s Pieces minus the brown ones)
  • 12 paper cups or several paper towels marked “Waste”
  • copies of the activity
  • 12 small metric rulers
  • one or more electronic balances (optional)
  • 12 sealable food storage bags marked “C. sweetus strain M”. Each bag should contain 4 each of the yellow, blue, green, orange, and red candies. There should be NO brown candies in the mix.
  • 12 waste containers (paper cups or paper towels)
  • 12 sets of colored pencils/markers (red, blue, orange, green and yellow)
  • a copy of the HHMI DVD Evolution: Constant Change and Common Threads, a DVD player or computer with a DVD drive and an LCD projector or monitor


  • Earth and Space Science
    • Earth's History
  • Life Sciences
    • Diversity of Life
      • Animals
      • Classification
    • Ecology
      • Populations
    • Evolution
      • Evidence for Evolution
      • Mechanisms of Evolution
    • Heredity and Genetics
      • Patterns of Heredity
  • Mathematics
    • Algebra
      • Patterns
    • Data Analysis and Probability
      • Data Analysis
      • Data Collection
      • Data Representation
      • Probability
    • Measurement
      • Rate
    • Number and Operations
    • Reasoning and Proof
    • Representation
  • The Nature of Technology
    • The Design Process
      • Problem Solving
  • The Nature of Science
    • The Scientific Process
      • Asking Questions
      • Conducting Investigations
      • Gathering Data
      • Formulating Explanations
      • Communicating Results

Informal Categories

  • Animals
  • Food and Cooking
  • Nature and Environment


To use this activity, learners need to:

  • see
  • see color
  • read
  • touch

Learning styles supported:

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


Components that are part of this resource:

Includes alignment to state and/or national standards:

This resource is part of:

Access Rights:

  • Free access


  • Colvard, Mary


  • All rights reserved, Howard Hughes Medical Institute, 2010